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LABORATORY MANUAL 

** L ZOOLOGY 

53 



BURNET 



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Glass CL L.53. 

Book, ,S ik- 
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COPYRIGHT DEPOSIT. 



A LABORATORY MANUAL 



OF 



ZOOLOGY 



BY 

MARGARETTA BURNET 

TEACHER OF BIOLOGY, WOODWARD HIGH SCHOOL 
CINCINNATI 



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NEW YORK •:• CINCINNATI •:• CHICAGO 

AMERICAN BOOK COMPANY 



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|UBRARYofGGM£Si3S 
j Two Copies Receivei 

J JAN 29 1908 
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Ji^iSS A XXc.. Nu. 
OOPY 8. 



Copyright, 190S, by 
MARGARETTA BURNET. 

Entered at Stationers' Hall, London. 



BURNET, LABORATORY MANUAL. 
W. P. I 



TO THE TEACHER 

Since the conditions under which laboratory work is 
done vary exceedingly, it is impossible to outline a course 
which will be equally acceptable to all teachers. This 
little book, therefore, presents more forms than any 
teacher will be likely to want, in the hope that from among 
them a selection may be made that is fairly satisfactory. 

The frog is taken up first among the vertebrates, and 
very fully, so that, if preferred, it may be used as an intro- 
ductory study instead of the crawfish. In this case, how- 
ever, the pupil will need the teacher's help in answering 
a few questions referring to work in the earlier part of 
the book. In the opinion of the author the crawfish is 
much the best form that can be used for such a study, 
since it is remarkably well adapted to bring out many 
fundamental ideas, while being less specialized in its 
organs than either frog or grasshopper, and standing more 
nearly midway between the highest and the lowest forms. 

The studies in experimental chemistry and physiology 
which follow this are to be used at the discretion of the 
teacher in those classes where no work has been done 
along this line in connection with human physiology. 
The experiments may be given as demonstrations by the 
teacher, or the simpler ones may be assigned to pupils 
for performance before the class. It is scarcely possible 
or even advisable to spend much time upon them, yet they 
help greatly to give a clear understanding of the vital 

3 



4 TO THE TEACHER 

processes of all animals. My own plan is to devote to 
them one period per week from the beginning of the year, 
both as a relief from the more intensive work of the 
introductory study and as being less tiresome to pupil and 
teacher taken so than in consecutive lessons. 

In my text-book " School Zoology " are lists of books 
for supplementary reading, and these lists have lately 
been revised ; but I wish especially to recommend to the 
teacher a book not mentioned there, Lloyd and Bigelow's 
"The Teaching of Biology," published by Longmans, 
Green & Co. In this may be found full and clear instruc- 
tions for obtaining, preparing, and caring for material of 
all kinds ; advice as to apparatus and equipment ; lists of 
dealers in zoological material and apparatus, and other 
most valuable information. 



CONTENTS 



PAGE 



The Compound Microscope .7 

Instructions for Drawings required in Laboratory Work i i 

Instructions for Writing up an Experiment . . . 12 

AN INTRODUCTORY STUDY 

The Crawfish 13 

The Crab 24 

The Pill Bug 24 

The Crawfish (Dissection) 25 

CHEMISTRY AND PHYSIOLOGY 

Chemistry 30 

Oxidation. . . 31 

Foods 34 

Diffusion and Osmosis - 37 

Digestion 39 

Circulation 40 

Tissues and Cells 43 

PROTOZOA 

Paramecium, the Slipper Animalcule 48 

Amceba 50 

vorticella, ttte bell animalcule 5 1 

PORIFERA 

Grantia, a Calcareous Sponge 52 

The Commercial Sponge 53 

CCELENTERATA 

The Fresh-water Hydra 54 

A Campanularian Hydroid 55 

5 



6 CONTENTS 

PAGE 

The Sea Anemone 57 

A Star Coral . . -58 

ECHINODERMATA 

The Starfish . . 59 

The Sea Urchin . .62 

VERMES 

The Earthworm 64 

The Leech . . .68 

The Sandworm (Nereis) 68 

MOLLUSCA 

The Fresh-water Mussel 70 

The Oyster 72 

The Snail 73 

ARTHROPODA 

The Grasshopper 75 

The Cecropia Moth 79 

Metamorphosis of Cecropia 81 

The Butterfly 82 

The Hawk Moth ....:.... 83 

Other Winged Insects 83 

The Spider 84 

The Centiped 84 

VERTEBRATA 

The Frog 86 

The Fish (Perch or Allied Form) .'..*.. 98 

The Snake 101 

The Lizard 103 

The Turtle 103 

The Bird 104 

A Mammal 109 

Vertebrate Skeletons 111 



THE COMPOUND MICROSCOPE 

Make out the following parts : 

a. The base, supporting a vertical column or pillar. 

b. The curved arm, attached to the pillar by a hinge. 

c. The horizontal stage (with its circular opening), fas- 
tened to the lower part of the arm. Upon the stage is 
placed the glass slide which holds the specimen to be 
examined. Of what use is the opening ? 

d. The pair of clips upon the stage. Of what use ? 

e. The diaphragm below the stage. Rotate the diaphragm 
and determine its use. 

/. The double mirror, attached to the arm behind the stage 
by a movable bar. Determine what movements are pos- 
sible for mirror and bar. How do its two faces differ? 
Which will throw a more concentrated light ? 

g. The cylinder, attached to the upper part of the arm. 

h. The draw tube, which slides in the cylinder. 

i. The coarse adjustment, which moves the draw tube up 
and down. This is regulated by a pair of large milled 
heads. Turn the milled heads of the coarse adjustment 
around halfway and back, and observe the distance 
traveled. 

j. The fine adjustment, regulated by a single milled head 
or thumbscrew. Compare the action of the fine adjust- 
ment with that of the coarse. What difference ? Make 
several turns in one direction. In which direction does 
the cylinder move if you turn the milled head in the 
direction of the hands of a clock ? 

7 



8 PRELIMINARY INSTRUCTIONS 

k. The eyepiece, at the upper end of the draw tube. Lift 
it out and examine it. How many lenses and how 
placed ? Why called eyepiece ? Return it to its place 
in the draw tube. 

/. The objectives, sets of lenses which may be attached by 
screwing to the lower end of the cylinder. They differ 
in magnifying power, and as two usually accompany the 
instrument, they are distinguished as high power (h. p.) 
and low power (1. p.). Why are they called objectives? 
When not in use they should be kept in their brass 
cases. Each is marked with a number (usually a frac- 
tion) upon its side, a corresponding number being upon 
the lid of the case. 

m. The nose piece (which may be double or triple), screwed 
to the lower end of the cylinder, having place for tw.o or 
three objectives, which may be brought in turn under 
the cylinder without the necessity of unscrewing and 
replacing. 

Lenses should never be touched, either with the hand or 
with any other object. They should be carefully pro- 
tected from dust when not in use. To wipe them, use 
clean, soft linen or chamois. 

All parts of the instrument must be kept dry, clean, and 
bright. 

In lifting, grasp the double pillar. 

To attach the objectives, raise the cylinder by the coarse 
adjustment until its lower end is two inches from the 
stage. Then use both hands to hold and screw in the 
objectives. If a double nose piece is present, attach 
both high power and low power. 

Place the microscope with the pillar towards you, grasp 
the base with one hand and the arm with the other, and 
move the arm towards you till the cylinder is so inclined 



THE COMPOUND MICROSCOPE 9 

that the eye can be brought over the eyepiece with the 
least effort. Be careful not to incline it so that the 
neck must bend when the eye is close to the eyepiece. 
Bend the body below the waist instead. 

With the right hand move the mirror till the concave side 
faces a point about halfway between the source of light 
and the hole in the diaphragm. Then, with the eye over 
the eyepiece, move the mirror slowly in various direc- 
tions till a bright light shines up through the tube. 

Never use the instrument in the direct sunlight. 

Mount some object on a slide in a drop of water, and place 
over it a cover glass, a tiny thin piece which gets its 
name from its use. 

Place the slide upon the stage, cover glass up, bringing 
the object directly over the center of the stage opening. 

Use first the low power. 

Watching the objective from one side, lower the cylinder 
by the coarse adjustment until the lens is within a sixth 
of an inch of the stage ; then, looking through the eye- 
piece, turn the milled head slowly in the opposite direc- 
tion until the object comes in sight. 

Then by the fine adjustment raise or lower the cylinder 
until the outlines are sharp and clear. Turn the milled 
head back and forth until you are sure the focus is exact. 

To focus with the high power, repeat these operations, be- 
ginning, however, with the lens as close to the slide as 
is possible without touching. The cover glass is likely to 
break if the lens strikes it, injuring both slide and lens. 

If the microscope has a double nose piece, focus with 1. p., 
then swing around the h. p. and focus again. 

In examining objects under the microscope, use the right 
and the left eye alternately and always keep both eyes 
open. At first this is difficult to do, but one may soon 



10 PRELIMINARY INSTRUCTIONS 

learn to see only what is under the lens and with much 
less strain than when constantly squinting. 

Test the relative magnifying powers, size of field, and posi- 
tion of parts of objects examined, under tripod lens, low 
power, and high power. 

To do this, write in the center of an inch square of white 
paper, with a fine pen and as small as possible, the let- 
ter "h." 

Upon a sheet of drawing paper write at the left-hand side 
a duplicate letter. Then side by side across the paper 
to the right of this make three circles the size of the 
opening in the tripod lens. 

Place the square slip under the lens and examine the " h." 
Copy it in the first circle as near as you can as it looks 
under the lens. 

Place the slip on a slide and examine with 1. p. What 
difference in the position of the letter ? Can you see the 
whole letter ? Move it until as much as possible of the 
upper part is in the field, and reproduce in the second 
circle. 

Now examine with h. p. Draw what you see in the third 
circle. How does this compare with what you saw with 

i. p.? 

If you should wish to examine details carefully, which 
power should you use ? Which should be used in find- 
ing an object ? Why ? 

Practice mounting and focusing, using a hair, a bit of 
cheese cloth, some pond scum, a few starch grains, etc. 

In mounting objects in water, be sure that both slide and 
cover glass are very clean. 

Put the object to be examined as near the center of the 
slide as possible, and if the object is thin, place not far 
from it a tiny bit of filter paper. 



DRAWINGS REQUIRED IN LABORATORY II 

Drop over the object a large drop of water. 

Taking the cover glass with forceps, place one edge on the 
slide at , one side of the drop, and very slowly lower it. 
If it is carefully done, all air bubbles will be excluded. 
If any should be present, lift the edge of the cover glass 
and lower it again. Then absorb any water outside the 
cover glass with filter paper. 

It requires care and practice to mount objects for micro- 
scopic examination. 



INSTRUCTIONS FOR DRAWINGS RE- 
QUIRED IN LABORATORY WORK 

Read carefully the instructions given in the lesson, and 
decide the answers to all questions referring to the object 
to be drawn. 

Then decide how large the drawing should be and where 
on the page it should be placed. If several drawings 
are to go on one page, decide the position and space to 
be given to each to make a fairly symmetrical page. 

Draw the outlines first in sharp, clear lines. 

Put in only such details as are necessary to illustrate the 
points of structure given in the lesson or called for in 
the questions. Do not waste time on any others. They 
detract from the clearness of your drawing. 

Do not shade any parts unless shading is absolutely neces- 
sary to show differences in structural features. 

These drawings must be scientific rather than artistic. 

They are not intended for practice in drawing, but to show 
whether you see and understand the structural peculiar- 
ities of the objects studied. 



12 PRELIMINARY INSTRUCTIONS 

INSTRUCTIONS FOR WRITING UP AN EXPER- 
IMENT IN THE NOTEBOOK 

The following order should be observed in writing up an 
experiment : 

a. Heading, a brief statement of the purpose of the experi- 
ment. 

b. Description of experiment, including materials and ap- 
paratus in the order in which used. 

c. Results obtained and time necessary to obtain them. 

d. Conclusions drawn from these results. 



AN INTRODUCTORY STUDY 
THE CRAWFISH 
Habits and Environment. 

(Field work) 

Go out and look for crawfishes and try to catch a few for 
closer study. While doing so, see how many of the fol- 
lowing questions you can answer, and make a note of the 
others. Make excursions to several places and at differ- 
ent hours of the day. 

When you have gathered all the information you can in 
regard to the habits of the animal, compare your conclu- 
sions with those of other pupils. You will probably then 
have a fairly correct idea of the habits of crawfishes in 
your own neighborhood, and the conditions which are 
favorable to them. But remember that as conditions 
vary not only in different parts of the country, but even 
in a limited region, the results of a few observations are 
not reliable. No fact should be accepted in science that 
has not been attested by repeated and varied observa- 
tions or experiments. 

Where did you find crawfishes ? 

In what ways did you capture them ? 

Did you find them active in the daytime ? If so, at what 
hours ? 

What depths of water do they seem to prefer ? 

Why are they found under rocks and shelving banks ? 

Why do they sometimes dig holes ? How can you recognize 
the holes ? 

13 



14 AN INTRODUCTORY STUDY 

When disturbed, how does the crawfish retreat? How is 

its retreat covered ? 
What is its food ? What organs are used in getting it ? 
Has the crawfish any enemies? How does it defend 
* itself? 

Is it solitary or gregarious in its habits? 
In what ways is the crawfish a beneficial animal ? 

External Features. 

(Alcoholic specimens) 

Compare the upper — dorsal — surface of the body with the 
lower — ventral — surface as to general shape and color- 
ing. What is the general coloring ? Is there any 
advantage in such a color? What difference between 
dorsal and ventral coloring ? Can you think of any 
advantage in this ? 

Into how many general regions is the body divided ? 

The forward — anterior — consists of head and thorax and 
is called the cephalothorax. The hinder — posterior — is 
the abdomen. Which is the more flexible ? Why ? 

Examine the ventral side of the cephalothorax. Can you 
see any evidence of segmentation ? What prevents its 
being flexed ? The shell or crust covering the cephalo- 
thorax is called the carapace. 

Examine the covering of other parts. Is the crust of these 
continuous ? How is it modified at the joints to permit 
movements ? Compare this shell with that of an oyster 
or clam. What advantages to the crawfish is such a* 
body covering ? What disadvantages ? 

Which is the right and which is the left side of the body ? 
How can you determine this for any animal ? 

Are the two sides alike ? Any animal with right and left 
sides corresponding and equal is bilaterally symmetrical. 



THE CRAWFISH 1 5 

Mention several animals, belonging to different groups 
that are bilaterally symmetrical. 

Examine the abdomen. Of how many ringlike segments 
does it consist ? How are they arranged to permit the 
bending of the abdomen ? 

In which direction do they overlap ? What advantage in 
this ? Can they bend so as to give a sidewise movement 
to the abdomen ? Examine a joint carefully and explain. 

The last division of the abdomen is the telson. This is 
the central piece of the tail, or caudal fin. Describe its 
shape. 

Every segment of the body bears a pair of appendages. 
Those of the abdomen are called swimmerets. How 
many pairs ? To which segment are the side pieces of 
the caudal fin attached ? Are they swimmerets ? 

The appendages that project from the sides of the carapace 
are legs. How many pairs ? The first are called che- 
lipeds. How do they differ from the other appendages, 
or walking legs? Compare right and left chelipeds as 
to size and shape. Of what advantage is it that they 
are rough on their inner edges ? Sometimes one cheliped 
is much smaller than the other. How can you account 
for this ? (In many of the lower animals lost parts grow 
again.) 

How many and which walking legs have pinchers? What 
terminates the others ? 

Examine the carapace. The head region is separated from 
the thoracic by the cervical groove. In which direction 
does it run ? 

The anterior penlike projection is the rostrum. 

Draw a dorsal view of the crawfish, natural size, and indicate 
carapace, rostrum, cervical groove, right cheliped, anterior 
abdominal segment, 6th right swimmeret, and telson. 



1 6 AN INTRODUCTORY STUDY 

The Abdomen. 

Carefully separate the 3rd abdominal segment from those 
before and behind it. The crust is composed of the fol- 
lowing parts : a dorsal tergum, with lateral extensions 
called pleura, and a ventral sternum. 

Find the peglike processes on this segment that articulate 
in pits in the next to form a hinge joint. Where are 
they ? 

Examine the swimmerets. To what part of the segment 
are they attached ? Each has a main stalk, protopod, 
and two branches, an outer, exopod, and an inner, endopod. 

How many joints in the protopod? How do exopod and 
endopod differ ? 

Lay the segment on its anterior edges, spread out the 
swimmerets, draw (natural size), and indicate the parts 
of the ring and its appendages. 

Compare the swimmerets of the 4th and 5th segments with 
those of the 3rd. Has each an exopod, endopod, and 
protopod ? 

Compare with these the 6th pair. Do the parts differ in 
number and arrangement or only in size and shape ? 

Can you account for these differences of development in 
any way ? Will an organ grow larger or smaller with 
exercise ? 

What advantages result from these differences in develop- 
ment ? 

Compare the swimmerets of the 1st and 2nd segments 
with those of the 3rd. If larger and peculiarly modified, 
they belong to a male ; if smaller and poorly developed, 
to a female. Which sex is your specimen ? 

Compare with those of other pupils until you can recognize 
male and female by these peculiarities. Which has the 
broader abdomen ? 



THE CRAWFISH 1/ 

Organs of the same general plan and position are homolo- 
gous. Is this true of the swimmerets ? 

Examine the under side of the telson for the anus, the 
exterior opening of the intestines. 

The Cephalothorax. 

Examine from the ventral side. Are the legs borne upon 
segments ? How many to each ? What part of the 
segment lies between their bases ? What replaces ter- 
gum and pleura for these segments ? 

Compare the 2nd and 3rd pairs of walking legs. Are 
there the same number of joints in each? Is the extra 
claw in the 2nd an extra piece or a prolongation of a 
part present in the 3rd ? 

Compare the chelipeds with the 2nd pair. Do they differ 
in number and arrangement of parts or only in their 
development ? Are they homologous ? 

To what use is each pair of legs put ? What advantage is 
gained in each case by its peculiarity in development ? 

Examine the joints of the legs. Are they capable of free 
movement or are they hinge joints ? Is the movement 
of two successive joints in the same direction? What 
advantage in this arrangement ? 

On the inside of the basal joints of one pair of legs are 
small openings, the outlets of the ducts from the repro- 
ductive organs. Upon which pair are they found in the 
male ? In the female ? 

With scissors cut away the loose part of the carapace on 
the right side, exposing the gills. What parts form the 
gill cavity ? 

Lay your specimen in water with the gills up and move 
each leg in turn freely. What effect has this upon the 
gills ? 

LAB. MAN. ZOOL. — 2 



1 8 AN INTRODUCTORY STUDY 

Study the arrangement of the gills. What is their position 
in relation to the legs ? To the length of the body ? Are 
any attached to the legs ? If so, how many ? To what 
are the others fastened ? 

What is the general character of the gills ? 

Find, towards the anterior end of the gill cavity, a double 
spoon-shaped organ, the gill scoop, or gill bailer, whose 
attachment and use will be determined later. 

Remove the 5th leg on this side. To do this separate this 
leg from the next, cut the membranes attached, and 
holding it by its basal joint pull it off. In the same 
manner remove the other right legs with the gills at- 
tached and lay them aside for comparison with other 
parts. 

The Mouth. 

Next examine the appendages immediately in front of the 
chelipeds. What position have they in relation to the 
mouth opening ? What relation does this opening bear 
to the length of the body ? (Is it longitudinal or trans- 
verse ? ) 

Lift the outermost appendage, a maxilliped, or foot jaw, to 
see a 2nd and 3rd pair. Are these directed forward, 
backward, or sidewise when at rest ? 

Compare the 3rd or outer maxilliped with the 3rd swim- 
meret. Has it a protopod ? Are exopod and endopod 
present? How many joints has its protopod? Is 
anything attached to it ? Is it homologous to the swim- 
meret ? 

Now compare this maxilliped with the 3rd leg, What part 
is present in the maxilliped that is absent in the leg ? 
(In the leg the exopod has disappeared.) What is at- 
tached to these two that is absent from the swimmeret ? 



THE CRAWFISH 19 

Remove the 2nd maxilliped and compare with the 3rd. Is 
any part lacking? Which parts are differently devel- 
oped ? 

Remove the 1st maxilliped and compare with the others. 
What part is not present that was found in connection 
with the other two ? What peculiar appendage is at- 
tached that is not found on the others ? 

The maxillipeds complete the thoracic appendages. How 
many segments in the thorax, as indicated by appen- 
dages ? 

The Head. 

The two pairs of appendages just beneath the maxillipeds 
are maxillae. How do they differ in texture from the 
maxillipeds ? 

Remove the maxillae one at a time, being very careful to 
get them entire. The remaining pair of mouth parts 
ape the true jaws, or mandibles. How do they differ in 
texture and color from the maxillae ? Look for a small 
appendage, a palpus, attached to and lying close to the 
mandible. On which surface does it lie ? Is it seg- 
mented ? 

What peculiarity have the opposed edges of the mandibles ? 
Remove them and add to the series of mouth parts. 
How many in all? The mandibles and maxillae are 
homologous with the other appendages but are so modi- 
fied that the homology is difficult to trace. 

Arrange all the mouth parts of the right side in a series 
and draw ( x 2). In connection with this draw the 3rd 
leg and 3rd swimmeret. 

The two longest appendages of the head are called an- 
tennae. 

Compare them as to flexibility and length with the legs. 



20 AN INTRODUCTORY STUDY » 

What difference in structure accounts for difference in 
flexibility ? Are protopod, endopod, and exopod pres- 
ent? To find the exopod, look for a piece just under 
the eye. What shape ? What probable use ? 

The other " feelers " are called antennules. Describe 
their structure. 

On the basal joint of each antennule look for an opening 
formerly supposed to be auditory, though there is doubt 
now whether hearing is the function of the organ to 
which it leads. How is the opening guarded ? 

Examine the eye. Is its stalk segmented ? Is it movable ? 
Can it be protruded and retracted ? What is its range ? 
Of what advantage to the animal is this arrangement ? 

Remove an eye and examine the black tip, or cornea, first 
with a lens and then with the compound microscope. 
Describe its appearance. Is it simple or compound ? 
Draw a group of its facets. 

There is some doubt as to whether the eyes and antennules 
are homologous with other appendages. Both of them 
are attached to the first segment of the body, while other 
segments bear but one pair of appendages. 

If they are excluded from the count, how many pairs of 
homologous appendages are there ? How many seg- 
ments in the whole body ? Parts that are modified to 
serve different uses are said to be specialized. Can this 
be said of the appendages of the crawfish ? What parts 
are specialized for swimming backwards ? For defense ? 

Remove any remaining appendages of the cephalothorax, 
and examine the sternal region of the head. What is its 
position ? Can you see any segmentation ? It is sup- 
posed to consist of five parts fused together. 

Next, carefully remove the carapace and examine the 
under side of the head region for the points of attach- 



THE CRAWFISH 21 

ment of the eyes, antennae, and antennules. Are they 
dorsal or ventral? 

The Skeleton. 

Clean out the soft parts from what remains of the thoracic 
segments and examine the interior. The partial parti- 
tions noticed there are inward projections of the crust. 

The crust of the crawfish is called an exoskeleton, or exter- 
nal skeleton. Is there any endoskeleton, or internal 
bony framework ? 

To test the character of the crust, first place a piece of the 
carapace in diluted hydrochloric acid, and note results. 
Hold a piece in a flame for a short time. What results ? 

Test in the same manner bits of clam shell and compare 
results. The substance dissolved by the acid is lime. 
What is the office of lime in a shell? 

What is the character of the remaining material of the 
crust after the lime has been removed with hydrochloric 
acid ? It consists of a horny substance called chitin. 
This was burned away in the flame. Of what use to the 
shell is this ? 

The Live Crawfish. 

Place a live crawfish in water deep enough to allow it 
to swim, and watch its movements. How does it use 
the caudal fin ? The swimmerets ? 

Catch the crawfish by the cephalothorax, and lift the head 
out of water. How does it use the various appendages ? 

What advantages in swimming backwards ? 

Watch the movements of the crawfish in walking. In 
which directions can it move ? What appendages are 
used ? How many together ? In what order ? Are the 
chelipeds used ? What difference between the way in 
which it uses legs with pinchers and those without ? 



22 AN INTRODUCTORY STUDY 

Test the strength of the muscles of the chelipeds by letting 
the crawfish grasp a pencil. Can it hold and bear its 
own weight ? Can it bear more ? 

Let it crawl upon a table. Does it move more or less 
easily than in water ? 

Place the crawfish in a bowl of clear water. With a 
pipette put a small drop of ink or carmine near the hin- 
der edge of the carapace. Is it drawn towards the 
gill cavity or expelled ? Put another drop near the 
mouth. In which direction does the water circulate ? 
This movement is kept up by the action of the gill bailer. 

To feed a crawfish, try bread, cheese, vegetables, bits of 
liver, earthworms, and other things. Does a crawfish 
prefer some kinds of food to others ? Will it eat a va- 
ried diet ? What appendages are used and how ? 

Test the sense of taste by placing sour or bitter substances 
on the mouth parts. 

What other senses might be excited if one used a pungent 
or irritating substance ? Would it make a good test ? 
Has a crawfish a sense of taste ? Would an animal that 
is omnivorous need a keen sense of taste ? 

To test the sense of smell, what sort of substances should 
be avoided ? Think of substances that would be likely 
to give reliable results and test. Has the crawfish a 
keen sense of smell ? What is the chief use to an ani- 
mal of a sense of smell ? 

To test the sense of touch, use a bristle upon crust, appen- 
dages (especially the fringes), eyes, antennae, and an- 
tennules. Which parts are sensitive ? 

What is the position of the antennae when the animal is 
swimming ? When walking ? When at rest ? Of what 
use? What is the probable use of antennules ? 

Watch a crawfish moving about. Is its sight keen ? When 



THE CRAWFISH 23 

it is swimming, can it see behind it ? Can it see food 
when it is feeding ? 

Bring your hand close to it. What results ? Touch one of 
the eyes with a pencil. What follows? Do the two 
eyes act in unison ? 

Put the aquarium where one end will be in a strong light 
and the other well shaded. Which does the crawfish 
prefer ? 

Crawfish may be captured at night by bringing a light to 
the edge of a stream and using a net to catch those 
attracted by it. 

Test the sense of hearing by various noises, being careful, 
however, not to cause perceptible vibrations of the air. 
What sense would be affected by such vibrations ? 
What would be the use of the sense of hearing to an 
animal like the crawfish ? 

If a female with eggs can be found, it is very interesting to 
watch the development of the young. 

How are the eggs carried ? Describe them. How large 
is the young crawfish when first hatched ? Does it re- 
semble the parent in structure, or does it undergo a 
metamorphosis ? 

Do the young leave the mother at once ? When they sepa- 
rate, do they ever return to her care ? Does she feed 
them ? What do they eat ? Do they ever kill one an- 
other ? 

If crawfishes are found ready to molt, watch the process. 

What is their condition just before molting occurs ? Re- 
cord the various stages of the process. 

Test the body covering of an animal that has just cast its 
shell. What is its condition ? Test it frequently for 
several days. How long does it take to harden ? What 
substance makes it hard ? What is meant by " soft 



24 AN INTRODUCTORY STUDY 

shell"? Why is molting necessary? Why is molting 
more frequent the first year of life than afterwards ? 



THE CRAB 

Compare with the crawfish in general plan of external parts. 

What differences in general form ? In relationship between 
cephalothorax and abdomen as to form, size, and posi- 
tion ? In abdominal segments ? In number and form of 
thoracic and abdominal appendages ? 

In some species what peculiarities has the 5th pair of legs ? 
Has a crab a caudal fin ? 

Judging from the development of appendages, what differ- 
ences must there be in the locomotion of crawfish and 
crab ? 

Compare the lobster and the shrimp ox prawn with the crab 
and crawfish. With which are they more closely related ? 



THE PILL BUG 

Compare the pill bug with the preceding forms. 

Does the carapace cover the thorax ? How can you dis- 
tinguish' thorax from abdomen ? How many segments 
in each ? 

How many pairs of legs has the pill bug ? Are they 
segmented ? Are they specialized for different uses 
as they are in the crawfish ? 

Look for a series of thin overlapping plates under the 
abdomen. . These are gills. 

Examine the head. Are the eyes stalked ? Are they 
compound ? 

Are there any antennae ? Antennules ? In what external 



THE CRAWFISH 25 

features does the pill bug resemble the crawfish ? 
What are the chief differences between them ? Which 
do you think the higher form ? 

THE CRAWFISH 

(Dissection of alcoholic specimen) 

Pin the crawfish dorsal side up in a dissecting pan, put- 
ting the pins through telson and each great claw. 

The Gills. 

Remove the carapace over the right gills, as before, and 
review your survey of the gills. How many are directly 
attached to the legs ? Remove a gill, and study it under 
a lens. What is its plan of structure ? 

Now remove the carapace, over the left gills, and cut off 
the gills from both cavities. Examine the walls sepa- 
rating the gill cavity from the internal organs. Can 
you see any vertical canals ? Were they connected with 
the gills ? These are blood vessels. 

The Heart. 

Remove the strip of carapace remaining over the thorax, 
being careful not to injure the delicate organs beneath. 

The organ first noticed is the heart. Describe its location. 
What shape and color ? 

Is there any space around the heart ? The sac in which 
the heart lies is the pericardium. The membrane form- 
ing its walls is so delicate that it is easily torn, and in 
preserved specimens is often hard to find. It incloses 
colorless fluid. Examine the walls of the heart. 

Look for blood vessels, arteries, leading from the heart 
In which direction do they run ? Can you find branches ? 
How is the heart held in place ? 



* 

26 AN INTRODUCTORY STUDY 



Reproductive Organs. 

Look for the reproductive organs beneath the heart. 
In the male they are called spermaries, in the female 
ovaries. What difference in shape, size, and color? 
(Compare a number of specimens.) 

Examine a number of females. If any dark-colored ova- 
ries are found, they contain eggs. The duct from the 
ovary is called the oviduct ; that from a spermary is the 
vas deferens. These ducts are difficult to trace, but 
their external openings were found in an earlier lesson. 
Where does each end ? 

Make a drawing of heart, arteries, and reproductive organs 
as far as you can see them from above, and designate 
each organ. 

Digestive Organs. 

Remove the heart and reproductive organs carefully and 
cut away the carapace over the head. The first organ 
noticed will be the stomach. What is its location? 
Shape ? Color ? 

Unpin the chelipeds, and with some flat, blunt instrument 
probe the mouth opening. The passage thus explored 
is the esophagus, or gullet. In what position does it lie ? 
With what does it connect ? 

Pin the specimen in place again. Find the pylorus, or out- 
let of the stomach. It connects with the intestine. 

On each side of the posterior border of the stomach lie 
glands, sometimes called " livers." Since their use or 
function is somewhat different from that of a true liver, 
they may more properly be called digestive glands. Find 
the duct from each gland. Where does it empty ? 

Draw the digestive organs of the thorax as seen from above, 



THE CRAWFISH 27 

leaving space to add the intestine later. Designate all 

parts. 
Remove the stomach, and examine its walls more carefully. 

What indications can you find that food is ground there ? 

Describe the apparatus. 
What peculiar provision is close to the pylorus ? What 

use should it serve ? 
Remove the digestive glands and pick one to pieces and 

examine with a lens. What is its plan of structure ? 
The intestine, the remaining digestive organ, being in the 

abdomen, must be studied later. 

Excretory Organs. 

In the front part of the body find the pair of glands whose 
openings are found at the base of the antennae. What 
color ? What shape ? These are the green glands, or 
organs of excretion. They correspond to the kidneys of 
the higher animals. 

The Abdominal Organs. 

Remove the tergal portions of the abdominal crust down to 

the telson. Examine the muscles which lie immediately 

beneath. What color? In which direction do they lie? 

Their anterior attachment is to the walls of the thorax; 

the posterior, to the terga of the segments of the abdomen. 
Which part is moved by them ? Is the movement controlled 

by the animal? If so, they are voluntary muscles; if 

not, involuntary. 
They shorten when in action. Do they bend or straighten 

the abdomen ? Why are they called extensors ? 
Lift them away and trace the intestine from pylorus to anus. 

Locate it. What shape ? Is it of uniform diameter ? 
Add the intestine to your drawing of digestive organs, and 

designate it. 



28 AN INTRODUCTORY STUDY 

The parts of the body through which food passes together^ 
form the alimentary canal. Mention them in their 
order. What outside or accessory organs are there ? 
The function of these is to furnish a fluid secretion to aid 
in digestion. 

Now remove the intestine and examine the muscles remain- 
ing. These muscles flex or bend the abdomen. Are they 
voluntary or involuntary ? 

How do flexors compare with extensors as to arrangement 
and thickness ? Which needs greater power ? Why ? 

Nervous System. 

Cut through the middle line of the flexor muscles, being 
careful not to cut too deep. When the muscle has been 
divided, push the halves apart and look for the nerve 
cord. Can you find any enlargements or ganglia ? If 
so, how many ? Where are they ? Are there any 
branches ? These are called nerves. Where given off ? 

Trace the nerve cord forward into the thorax. Is it as ex- 
posed in this region ? 

Break away any hard parts that cover it and trace to the 
head. Is the cord single through abdomen and thorax ? 

How many ganglia in the thorax ? Are there nerve 
branches from these ? 

Just behind the esophagus find a large ganglion whose 
nerves supply the mouth parts. Trace forward from 
this two divisions of the cord. Why is this division 
necessary ? Where is the ganglion in which they again 
unite ? 

From which ganglion do nerves originate to supply eyes 
and antennae ? This is sometimes called the brain. 

Draw a diagram of the nervous system, marking the vari- 
ous ganglia and their branching nerves. 



THE CRAWFISH 29 

Reproduction. 

The germ cell or oosperm of any animal is produced in the 
following manner. A minute and active male reproduc- 
tive cell called a sperm reaches and penetrates a larger 
female reproductive cell called the ovum, and fusing 
with its nucleus is said to fertilize it. In what organ 
are the sperms developed ? In what organ are the 
ova developed? 

The development of the oosperm of the crawfish is very 
peculiar, and since that of starfish or mollusk eggs is 
much more typical of the process in most animals, it is 
better to study one of these. 

Examine a slide showing starfish or mollusk eggs. Look 
for a single cell. Is it nucleated ? Has it a distinct 
membranous wall ? Look for cells in process of dividing. 
Has each division a nucleus ? 

Look for a group of four cells. How produced ? Is the 
second division in the same plane as the first ? 

Can you find any groups of eight or more cells ? How 
arranged ? A mass of cells forms the morula stage. 

The cells next become arranged in a hollow sphere, the 
blastula. 

Following this, one half of the sphere doubles in to line the 
other half. This forms a cup-like body, the gastrula, of 
two cell layers. 

Beyond this the process differs greatly in different animals, 
the cells becoming more and more specialized to form the 
various tissues. 

The developing young animal is called the embryo. 

Make drawings to show the successive stages in the embryo 
you have been studying. 



CHEMISTRY 

(Optional) 

To understand the various vital processes going on in the 
body of an animal, such as digestion, circulation, respira- 
tion, etc., some knowledge of elementary chemistry is 
necessary; the following experiments will be found 
helpful. 

Acids and Alkalies. 

(Materials needed : several jars or common tumblers, soda, 
potash, vinegar, hydrochloric acid, starch paste, olive oil, 
white of egg, sugar, and pink and blue litmus paper.) 

Make a strong soda solution. Taste it. Test with pink 
and blue litmus paper. Which changes color in the 
soda solution ? Does the other change ? 

Test in the same way a potash solution. Any substance 
which changes pink litmus paper to blue is an alkali, 
and a solution containing it is alkaline. 

Now make a weak solution of hydrochloric acid (HC1). 
Taste a drop of the solution. Test with the pink and 
blue litmus paper. Which is affected by the acid ? 

Test in the same way another acid solution, such as a 
vinegar solution. What is the effect of acids on the lit- 
mus paper ? How would you define an acid ? 

Now test for the presence of acid or alkali, white of egg, 
sugar solution, starch paste, olive oil, etc. 

Any substance which changes neither pink nor blue litmus 
paper is said to be neutral. Which of the substances 
just tested are neutrals ? 

30 



OXIDATION 31 

Chemical Combinations. 

(Materials needed: a glass, a cup, lime phosphate, soda, 

and hydrochloric acid.) 
Mix with water a little lime phosphate, shake well, and 

allow it to stand a few minutes. Does the lime dissolve ? 
Now add a few drops of dilute HC1 and shake. What 

change takes place ? 
A combination has taken place which is a chemical one. 
Another experiment to illustrate the same sort of action is 

the following : 
Into half a cup of soda solution pour slowly a small amount 

of solution of HC1. What happens ? 
Keep adding the acid with a pipette till foaming ceases. 

Test with pink and blue litmus paper and continue until 

the acid and alkali neutralize each other. 
Taste the resulting solution. Boil it until all the water has 

evaporated. Is the residue soda ? Is acid left ? 
Besides the common salt thus left a gas was formed whose 

escape into the air causes effervescence. 
When substances which are put together lose their original 

characteristics and form new substances, the combination 

is a chemical one and the force which causes it is called 

affinity. 
In nature such combinations and their resulting changes 

are constantly occurring, and the vital processes of both 

plants and animals depend upon them. 

OXIDATION 

(Optional) 

Carbon. 

(Material and apparatus needed : several test tubes, a 
match, some sugar, starch, white of Qgg y and lard or 
tallow.) 



32 CHEMISTRY AND PHYSIOLOGY 

Burn a match until it is charred. Describe the substance left. , 

Heat in a test tube a little sugar. Watch the' tube care- 
fully for moisture and when that has disappeared exam- 
ine the contents of the tube. 

In the same way examine fat, starch, and white of egg. 
What characteristics common to the residue of each ? 

The element remaining is carbon, which is found in com- 
bination with other elements in the substances tested. 

What substances did they give off while being heated ? 
Water consists of two elements, hydrogen and oxygen. 

What three elements, then, enter into combination in wood, 
starch, sugar, fat, and white of egg? 

The Burning of Carbonaceous Substances. 

(Material and apparatus needed : two flat-bottomed dishes, 

two bell jars whose diameter is slightly less than that of 

the dishes, two tumblers, a candle, some limewater.) 
Set a vial of clear limewater in each of two flat-bottomed 

dishes, and beside one of the vials put a lighted candle, 

stuck in place by a drop of the wax. 
Now put an inch of water in the bottom of each dish and 

cover the vials and candle with bell jars whose edges 

will be immersed in the water. 
Does the water rise in the jars to the level of that outside ? 

Explain. 
As the candle burns, watch the inside surface of the jars. 

Does either change ? 
What happens to the candle ? Is there any change in the 

outside water ? 
After a moment or two lift the bell jars. Has any change 

occurred in the limewater in either jar? If limewater 

becomes milky, this is due to carbon dioxide gas which 

has been absorbed by it. 



OXIDATION 33 

Whence came this gas ? What two substances are formed 

in burning the candle ? 
Why did the water rise in one jar and not in the other ? 
The substance used up was oxygen gas (O) which forms 

about 21 % of air. This unites with carbon (C) to form 

carbon dioxide gas (C0 2 ). Where does the carbon come 

from ? 
Moisture also was formed. This consists of hydrogen (H) 

and oxygen. 
Where were these elements obtained ? 
What happens to the candle as it burns ? 
The union of O with other elements is called oxidation. 

The substance of the candle was oxidized. 
What two substances are the result of the oxidation of 

carbonaceous material ? 
The Gas Exchange in Breathing. 
(Material and apparatus needed : a glass, a glass tube, a 

physician's thermometer, a little limewater.) 
Put a little limewater in a glass. Into this put one end of 

a glass tube and blow through the tube into the water. 
After a moment what change takes place in the limewater ? 

What gas is given off in the breath ? 
Is this gas present in the same quantity in inspired air ? 

How can you tell ? 
Where is the C0 2 formed that is breathed out ? Where 

does the O come from ? The C ? 
Breathe in a cold glass. What results ? 
Is there as much moisture in inhaled as in exhaled air? 

How can you prove this ? Whence came the moisture ? 
What two substances are formed in the body and given 

out in the breath ? 
What process is going on in the body in connection with 

breathing ? 

LAB. MAN. ZOOL. — 3 



34 CHEMISTRY AND PHYSIOLOGY 

What elements does the body lose ? 

What common term is applied to the oxidation of the 
candle ? 

If we shut off air, will burning take place ? 

What are the beneficial results of burning in the case of a 
furnace ? What in the case of an engine ? 

Could an engine run without heat ? Could heat be ob- 
tained without O ? 

With a thermometer test the temperature of the body- 
under the tongue. How high is the mercury ? Is it 
about the same for all pupils ? 

Compare this with the temperature of the air in the room. 
Whence comes the extra heat ? 

Exercise vigorously for a moment with the thermometer 
in the mouth. Does the mercury rise any ? What is 
one result of exercise ? 

If all of the oxygen were exhausted from the air we 
breathe, would the body remain warm ? 

What process is increased in the body by exercise ? 

What is the purpose of breathing ? 

Animals which breathe by gills get O from air dissolved 
in the water. Can they use as much as man ? 

Is oxidation an essential life process ? 

To understand further how oxidation occurs in the body of 
any animal, it will be necessary to understand how O 
gets from the inspired air to the tissues of the body, 
which involves several other steps or processes. 

FOODS 

(Optional) 

How does an animal replace the materials exhausted from 
the body in oxidation ? 



FOODS 35 

Give two reasons why a young animal needs more food in 
proportion than an average adult. 

What elements have your experiments shown to be neces- 
sary to the body ? 

Would you consider water a food ? 

Can you think of any mineral substance greatly needed by 
the crawfish ? 

There is another element which enters into combination 
with others to form part of our bodies, the gas nitrogen 
(N). It forms about yy% of the air, and when the 
oxygen is exhausted is left nearly pure. Will it burn ? 
Will it assist burning ? 

Nitrogen enters into combination with other elements to 
form protoplasm, of which all animal cells consist. 

State all the reasons why an animal needs food. 

Are the elements needed taken free or in compounds ? 

The compounds which contain nitrogen are called nitrog- 
enous or albuminous foods, or proteids ; those that 
contain only carbon, hydrogen, and oxygen are called 
carbonaceous. 

To test for Proteids. 

(Material and apparatus needed : four test tubes, Millon's 
reagent, an Qgg, sugar, starch, mutton tallow, seeds, fruits, 
vegetables, white muscle of some animal, milk curd.) 

Boil an egg hard and place the white, which is nearly pure 
albumen, in a test tube. Pour a little Millon's reagent 
on it and heat over a flame. What results ? 

Put into separate test tubes dilute starch paste, grape 
sugar, and mutton tallow, and treat each with the re- 
agent. 

Are the results the same ? What do they show ? 

Why is Millon's reagent a reliable test for albumen ? 



36 CHEMISTRY AND PHYSIOLOGY 

Now test in the same manner various seeds, vegetables, 
and fruits, having first boiled and crushed them. What 
are your conclusions ? Do they contain albumen ? 

Test the white muscle of the crawfish or some other animal, 
or any other light-colored animal tissue. 

Test milk curds. 

What class of foods is most strongly nitrogenous ? 

The carbonaceous foods are starch, sugar, and fat or oil. 

To test for Starch. 

(Material needed : four test tubes, solution of iodine, foods 

as above.) 
Make a thin boiled starch paste, and when it is cool drop 

into it a few drops of weak solution of iodine and note 

the color reaction. 
Test, in the same manner, white of egg, sugar, and mutton 

tallow. Do they show the same reaction ? 
What is the only one of these four foods that turns blue 

when tested with iodine ? 
Now test in the same way (after boiling and crushing) a 

number of seeds, vegetables, and fruits (both ripe and 

green) ; also some light-colored animal tissue. Is starch 

present in quantity in any one ? Is it present in animal 

tissues ? 

To test for Grape Sugar. 

(Material needed : four test tubes, Fehling's solution, foods 
as before.) 

Make a saturated solution of grape sugar or glucose, put 
a little in a test tube, and add about 20 % of a strong 
caustic soda solution, followed by a few drops of a 1 % 
solution of copper sulphate, which together constitute 
Fehling's solution. What color results ? 



DIFFUSION AND OSMOSIS 37 

Bring to a boil and note changes in color. What is the 
final color ? 

Can you see any deposit of sediment ? 

Test in the same way dilute starch paste, white of Qgg y and 
tallow. Does any one show the color reaction of the 
grape sugar ? 

Is this a good test for grape sugar ? Why ? 

Why do we use grape sugar instead of ordinary sugar ? 

Test a number of foods for grape sugar, first boiling each . 
in a test tube, adding the caustic soda and copper sul- 
phate, and boiling again. 

Is grape sugar found in animal substances ? In all vege- 
tables and fruits ? 

To test for Fats or Oils. 

(Materials needed: two plates, unglazed paper, foods as 

before.) 
Place on a piece of unglazed paper a bit of tallow and heat 

it. What effect on the paper ? 
Test in the same way sugar, starch, and boiled white of 

egg, putting them on a plate lined with the paper and 

covered with another plate, and heating in a slow oven 

for half an hour. 
Remove and shake off the paper. Can you see any stains ? 

If so, do they resemble those made by the tallow ? 
Test in the same way various foods. Which contain oil 

or fat ? Do vegetables ? Do fruits ? Whence come 

most of our fatty foods ? 

DIFFUSION AND OSMOSIS 

(Optional) 

Apparatus and material needed : For experiment (£), long, 
shallow dish, teaspoon, sugar, salt. 



38 CHEMISTRY AND PHYSIOLOGY 

For experiment (c), two tall, wide-mouthed bottles fitted 
with tight corks, two thistle tubes, parchment paper, 
bits of marble, hydrochloric acid. 

For experiment (d), several small, wide-mouthed vials, as 
many flat-bottomed dishes, parchment paper, salt, grape 
sugar, raw and boiled starch paste, raw white of egg, 
olive oil, soda, vinegar, Millon's reagent, iodine, Fehling's 
solution, litmus paper. 

(a) Shut off all drafts in a room. Turn on the gas in one 
burner for a minute, and determine how soon its pres- 
ence may be detected at some distance. 

How soon will the gas be so dispersed that its odor is 
about equally distributed all over the room ? 

This mingling of gases is called diffusion. 

(J?) Make a strong sugar solution in a long, shallow dish. 
Introduce as gently as possible into one end a teaspoon- 
ful of a strong salt solution, and taste the liquid at the 
other end after a moment or two. Does the salt solu- 
tion diffuse in the sugar solution ? 

What kinds of substances may diffuse ? 

(c) Perforate the corks of two bottles and insert through 
each the tube of a thistle tube, making the perforation 
as air-tight as possible, but be careful not to push the 
tube very far through. 

Cover the bulb end of each thistle tube with animal mem- 
brane or parchment paper, and keep one moist and the 
other dry. 

Fill each bottle about one third full of bits of lime. Cover 
with water, add a teaspoonf ul of strong hydrochloric acid, 
cork tightly, and observe results. Account for them. 

(d) Fill a wide-mouthed vial with strong salt solution, cover 
its mouth with membrane, and lay it on its side in a dish 
of pure water. 



DIGESTION 39 

At the end of twenty-four hours taste the water in the 
dish. What has occurred ? 

In the same way set up bottles containing grape sugar 
solution, raw and boiled starch, white of egg, oil or 
melted butter, soda solution, vinegar, or other acid solu- 
tion. Set up one bottle containing soda solution in a 
dish containing vinegar. 

Take a little of the outside liquid from the vessel in which 
the grape sugar solution was placed. Test for grape 
sugar. Does grape sugar diffuse readily through a mem- 
brane ? 

Test also the liquid outside of each of the other vials for 
the solution within the vial. Which solutions pass readily 
through the membrane ? Which do not pass at all ? 
Will two fluids mingle through a membrane ? Such 
mingling is called osmosis. 

To show the direction in which the greater flow takes 
place, cover the bulb end of a thistle tube with parch- 
ment paper. Then through the tube end half fill the 
bulb with thick sugar sirup, and support the thistle tube 
in a vessel of water so that the fluids inside and outside 
the tube are at first at the same level. 

Examine every fifteen minutes for an hour or two. Is the 
current greatest toward the denser or thinner liquid ? 

These experiments in diffusion and osmosis will help to 
explain how food and oxygen reach all parts of the body 
and how wastes are removed. 

DIGESTION 

(Optional) 

In order that starch, fat, and proteids may pass through 
the membranes of the alimentary canal and the walls of 



40 CHEMISTRY AND PHYSIOLOGY 

the blood vessels into the blood, it is evident that some 
change must occur in them. 

Such a change occurs in the processes of digestion by- 
means of various digestive fluids, which have the power 
of transforming these foods into liquid or soluble sub- 
stances which can easily enter the blood and pass again 
from that to the cells of the body or be oxidized in it to 
give heat and energy. 

Experiments to show the action of the various digestive 
fluids may be found in Eddy's " Experimental Physiology 
and Anatomy." 

CIRCULATION 

(Optional) 

Examine a drop of human blood under the microscope. 

To obtain this, bind a finger tightly at its base for a few 
moments till it looks dark and slightly swollen. Then, 
with a sharp needle that has been sterilized in a flame, 
prick the finger and put the drop with a drop of water 
on the slide. Use first 1. p. and then h. p. 

The solid bodies are the blood cells, or corpuscles. 

What two kinds ? 

Describe the more numerous ones, giving shape, size, and 
color. These are the red corpuscles and give the color 
to the blood of all the higher animals. They take up O 
readily and as readily give it off. 

If the drop is carefully examined, other less numerous and 
larger white corpuscles may be seen. What shape? Is 
the shape constant ? 

The fluid of the blood is plasma, and in it are carried the 
dissolved foods. 

By what processes does food enter and leave the blood ? 
By what process does oxygen enter and leave it ? 



CIRCULATION 41 

The flow of blood may be seen under the microscope in 

the webbing of a frog's foot or a fish's tail where the 

vessels are tiny and their walls thin. The same arrange- 
ment will serve for either. 
Get a thin board or a heavy cardboard, 8 or 10 inches 

long by 6 wide. 
One inch from the center of one end, cut a hole about the 

size of the opening in the stage of the microscope. 
Lay the board with this end on the stage and the hole 

properly adjusted, and prop the other end so the board 

will be level. 
Now wrap a small live minnow or goldfish in a piece of 

wet cloth, leaving the tail free. 
Lay the fish on the board, bringing the tail over the hole. 
Spread it out and with a couple of pins fasten it so as to 

stretch it as tight as possible. 
Examine with h. p. Can you see the movement of the 

corpuscles ? 
Can you see the direction in which the blood flows in the 

tiny vessels ? 
Find two vessels which unite to form one. The two 

smaller are capillaries, the one larger a vein. 
Find a blood vessel which divides to form capillaries. 

This is an artery. 
Identify as many arteries and veins as you can see. 
Instead of the fish's tail, a frog's foot may be used, in 

which case, however, it will be necessary to use ether to 

keep the animal from jerking and tearing the foot. 
Hold the frog in a wet towel, leaving it loose over the head 

and the feet free. 
Pour a little ether on a bit of cotton, put it over the frog's 

nostrils, and cover closely with the towel. 
When the legs will hang limp and no longer jerk when 



42 CHEMISTRY AND PHYSIOLOGY 

pulled, lay the frog in the towel on the board, spread 

the foot over the hole, and pin so as to stretch it tight. 
Examine as above. 
If the flow is too slow, move the cotton away from the 

frog's nostrils for a time. 
By moving the cotton nearer to or farther from the nostrils 

as the case requires, renewing the ether, etc., the animal 

may be kept for hours in condition to demonstrate for 

circulation. 
The heart is a pump to force the blood about the body. 
To show the pumping of the heart, kill a frog by means of 

ether and quickly open the cavity containing the vital 

organs by cutting just to the left of the median line on 

the ventral side. 
Touch the heart with the points of the forceps and observe 

results. 
Study and describe the movement of the heart. 
Cut all connecting blood vessels and remove the heart to 

a watch glass containing a i % salt solution. Observe 

that its beating is renewed. 
Open the heart and observe its cavities ; the upper is the 

auricle ; the lower is the ventricle. 
The blood vessels carrying blood away from it are called 

arteries without regard to the kind of blood carried. 
Vessels carrying blood towards the heart are veins. 
Connecting them are tiny vessels called what ? 
Through the walls of which will diffusion and osmosis take 

place most easily ? 
Which will reach all the cells of the body ? 
In the crawfish where are the capillaries distributed which 

receive O and give off C0 2 ? 
Where are those which absorb digested food ? 
What exchanges take place between the blood in the 



TISSUES AND CELLS 43 

other capillaries of the body and the tissues among 
which they lie ? 

TISSUES AND CELLS 

(Optional) 

Each different substance of which the body of an animal 
is composed is called a tissue. 

In order to understand its composition, it should first be 
examined with the naked eye and then a bit should be 
mounted and examined under the microscope. 

Frequently it is necessary to stain a section for examination, 
since it would be too nearly transparent to be easily 
seen. When a stain is used, some portions^darken more 
than others, and thus details are more perceptible. 

(Materials needed: set of slides showing animal tissues; 
same tissues obtained from a butcher's.) 

Cartilage. 

Ope of the simplest tissues found in the higher animals is 
cartilage, which forms a padding at the joints and is the 
earliest stage of bone. 

Examine a bit obtained from a butcher. What color ? Is 
it opaque ? Is it soft ? Elastic or inelastic ? Can you 
think of any other properties it possesses ? 

Place under the microscope a prepared slide of hyaline 
cartilage and examine carefully with the 1. p. 

Can you see any dark dots ? Are they numerous ? 

Are they uniformly scattered ? Describe their arrange- 
ment. 

Examine with h. p. Each dot is called a cell. What is 
the shape of a cell? 

Make out a smaller spot in each cell, the nucleus. 



44 CHEMISTRY AND PHYSIOLOGY 

The substance of the cell is albuminous and is called proto- 
plasm. 

Can you find any cell with more than one nucleus ? If so, 
the cell is beginning to divide. 

Can you find two cells that have just divided ? 

Can you find any group of more than two ? 

Cells multiply or propagate themselves by division. 

The substance in which the cells are imbedded is called 
the matrix and is built by them. What is the appear- 
ance of the matrix of cartilage ? 

Draw a group of cells. 

Epithelium. 

Examine with 1. p. and then with h. p. a prepared slide. 

What shape are the cells ? Are they imbedded in a matrix ? 
How arranged? 

Can you find a nucleus in each cell ? 

Draw a group of cells. 

Epithelium lines the internal organs of every animal. It 
also covers the gills of water animals. 

Put a bit of the gill from a live oyster or other gill-breath- 
ing animal under the microscope and examine the epithe- 
lium. Can you see any parts in movement ? 

The very slender threads are called cilia and are merely 
prolongations of the protoplasm. Do they seem to have 
any definite rule of movement ? Describe it. 

Draw a few cells much enlarged. 

Muscle. 

To determine some of the characteristics of muscle, put 
your left hand over the upper inner part of the right 
arm, and flexing and then straightening the elbow, feel 
the changes that take place in the biceps muscle. 

The soft part of the muscle is called the belly. 



TISSUES AND CELLS 45 

The cords which fasten it to bone are called tendons. 

The end which moves the least is the origin, the other end 
the insertion. 

Flexing and straightening the elbow joint, try to find the 
origin and insertion of the biceps. 

The work of a muscle consists in contraction : its rest is 
relaxation. 

When is the muscle longest ? Thickest ? Firmest ? 

When the caudal fin of the crawfish is bent under the 
body, which set of muscles is contracted and which 
relaxed ? 

Where is the origin and where the insertion of each set ? 

How does the color of the muscle of the crawfish differ 
from that of lean meat ? The muscles of the higher ani- 
mals ? 

Examine a bit of muscle. Can you see any divisions? 
These divisions are bundles of cells. 

What keeps the bundles distinct ? 

What is the shape of a bundle ? In which direction does 
it lie in the muscle ? 

Examine a bit under 1. p. and then h. p. 

Can you see any divisions ? What shape ? These di- 
visions, although cells, are called fibers. Why ? 

Can you see any cross markings ? These are called striae 
and muscle having such markings is said to be striated. 

Draw several fibers much enlarged to show striations. 

Since striated muscles are controlled by the will of the an- 
imal, they are also said to be voluntary. Muscles that 
are not are involuntary. 

What parts of the body of any animal are moved by vol- 
untary muscles ? 

Where are the involuntary found ? 

Examine a slide of involuntary muscle tissue with 1. p. and 



46 CHEMISTRY AND PHYSIOLOGY 

then h. p. Are the cells striated? Nucleated? How, 
arranged ? 
Draw a group. 

Tendon. 

Examine a bit obtained from a butcher's. Its color. Is 
it elastic ? Is it easily torn or broken ? What proper- 
ties does it possess ? 

Examine a bit under h. p. Of what does tendon chiefly 
consist ? This is inelastic connective tissue. 

Examine a slide showing a bit of the membrane lining the 
internal organs. This is elastic connective tissue. 

Can you make out fibers ? How arranged? 

Can you see any cells ? How distinguished from the fibers ? 

Are the fibers of connective tissue cellular or intercellular? 

Draw a bit of elastic tissue showing cells and fibers. 

Liver. 

Examine a bit with a lens. Compare with the texture of 
muscle ; of cartilage. Examine under 1. p. and then un- 
der h. p. a slide showing liver. Is it composed of cells ? 

Draw a few. If nucleus is visible, indicate it in your drawing. 

Bone. 

Examine a cross section under h. p. How does it differ 
in appearance from cartilage ? 

The dark spots show the location of bone cells. What is 
the character of the matrix of bone cells ? 

The larger spots or openings show the location of the Ha- 
versian canals, through which run blood vessels. How 
are the cells arranged in relation to these canals ? 

Nervous Tissue. 

What is the color of the nervous tissue of the crawfish ? 
It is the same in all animals. 



TISSUES AND CELLS 47 

Of what parts is the nervous system of the crawfish com- 
posed ? 

The ganglia are collections of cells. 

Examine with L p. a slide showing nerve cells. Are they 
a compact mass as in muscle, side by side as in epithe- 
lium, or imbedded in a matrix as in cartilage? 

Examine with h. p. How do nerve cells compare in shape 
with muscle cells ? With cartilage cells ? 

Can you see any prolongations? These extend as fibers, 
either connecting one nerve cell with another or with 
some other part of the body. 

Draw a group of cells much enlarged and mark parts. 

Examine a cross section of a nerve. It is simply a bundle 
of fibers. Can you make out cut ends of fibers ? 

Of what minute structures are all animal tissues wholly or 
in part composed ? 

How do they resemble each other ? How do they differ ? 

Can you think of any causes for their differentiation ? 
Any advantages in it ? 



PARAMECIUM, THE SLIPPER 
ANIMALCULE 

Paramecium is a microscopic form that feeds chiefly on 
bacteria and other forms of plant life or decaying 
organic matter in the water. Will it be found in pure 
or in stagnant water? How may Paramecium be culti- 
vated in the laboratory? 

Examine with 1. p. a drop of slime from a culture for rather 
slipper-shaped, swiftly moving forms. Are they alike ? 
Which end is anterior and which is posterior ? 

Can they swim backwards ? Sidewise? Is the movement 
aimless or does it evince any definite purpose ? Describe 
it. 

Can you distinguish an oblique groove on one side of the 
body? This connects with the interior of the body by 
means of the gullet and constitutes a sort of mouth. In 
which direction does its external opening point ? 

Can you discover in the interior of some Paramecia large 
clear spots that are not seen in others ? 

Watch one animal closely, and if possible see that this 
spot comes and goes. It is called the pulsating vacuole. 
Its function is believed to be excretory. 

Some species of Paramecia have one and some two pulsat- 
ing vacuoles. How many has the one you are 
examining ? 

Examine with h. p. a Can you make out any food balls, 
dark round masses often surrounded by a little water ? 

1 To bring out the food balls make a strong carmine solution, add it to a 
culture, and examine after twenty-four hours. 

4 8 



PARAMECIUM, THE SLIPPER ANIMALCULE 49 

Are they confined to any definite region of the body ? 
Compare several animals to be sure of this. 

Can you see any distinction between parts of the body 
substance ? 

It consists of a jellylike protoplasm of which the outer thin 
layer is called the ectosarc, and the more fluid interior 
the endosarc. Which is the more granular ? 

1 Can you distinguish a membrane covering the ectosarc ? 

Can you make out cilia by means of which the animal 
moves ? Are there cilia in the mouth opening ? Are all 
the cilia of equal length ? How is food obtained ? 

Examine a slide that has been stained 2 and look for a lens- 
shaped body, the nucleus, near the center of the animal. 

If possible find a smaller body, the micronucleus, near the 
nucleus. 

Draw a Paramecium, making your drawing two inches in 
length, and put in all parts that you have seen. 

Reproduction. 

Possibly you may have seen, among the Paramecia you 
have examined, forms that seem to be dividing in half. 
If so, make out if possible a division into halves of 
nucleus and micronucleus. 

When this division is complete, the other material of the 
body, the cytoplasm, divides also, and thus two individuals 
are formed. This is reproduction by fission or division. 

1 To slacken the movement of these swiftly moving forms, make a mucilage 
of gelatine or gum arabic of about the consistency of a thick sirup. Upon a 
slide put a ring of this about the size of the cover glass, and in its center a 
drop of the culture containing Paramecia. If the mucilage is of the right 
consistency, the movements of these animals will be retarded sufficiently for 
the eye to follow them easily. 

2 To bring out the nucleus and micronucleus, make a 1% solution of acetic 
acid to which add 10% of methyl green and run a drop or two under the 
cover glass. 

LAB. MAN. ZOOL. — 4 



50 PROTOZOA 

Can you find two Paramecia with their grooved surfaces 
closely applied to each other ? When this occurs, a 
process known as conjugation is taking place. The 
nucleus of each animal breaks up. This is followed by 
the division of each micronucleus into four parts. Two 
of these and all of the parts of the nucleus disappear, 
being absorbed into the substance of the cytoplasm. 

There are still two parts of the micronucleus visible in 
each Paramecium. One of these from each animal passes 
over and unites with the remaining part of the micro- 
nucleus of the other animal. 

Then the two Paramecia separate after this exchange. 
The new nucleus formed by the union of parts of the 
micronuclei of the two conjugating individuals divides 
to form nucleus and micronucleus. After a time repro- 
duction by simple division occurs. 

AMOEBA 

In Protozoan cultures may sometimes be found another 

form, the Amoeba, which seems a mere quiet drop of 

protoplasm. 
Watched closely its form will be seen to change with a 

slow movement. 
Does it possess ectosarc and endosarc ? Body membrane? 

Nucleus ? Contractile vacuole ? Cilia ? 
How does it move ? Has it any mouth ? How is food 

taken in ? 
Bulging parts are called pseudopodia. 
Draw an Amoeba an inch in diameter and mark all parts. 
Draw several forms to show successive changes as it 

moves. 



VORTICELLA, THE BELL ANIMALCULE 

Sometimes Vorticella may be found in the cultures with 

other Protozoans. Look for bell-shaped forms. Are 

they free-moving ? 
Describe shape and attachment. 
Has the animal ectosarc and endosarc ? Body membrane ? 

Nucleus ? Contractile vacuoles ? 
If cilia are present, locate and describe. 
Locate the mouth and gullet. 
Tap on the slide with a pencil. What happens ? Can the 

Vorticella change its shape ? 
Draw a Vorticella as large relatively as Paramecium and 

Amoeba. 
Can you see any evidences of division into cells in the 

bodies of the animals you have just studied ? 
What is their food ? How and where digested ? 
How transformed into new substances ? 
Where do they get the energy by which they move ? 
How do they obtain ? 
How are wastes eliminated ? 
Can they direct their movements ? Can they distinguish 

food ? 
Advanced Work. Topics suggested for further investi- 
gation, supplementary reading, and discussion : 
Examination of material from cultures for other Protozoans 

and comparison with forms already studied. 
Colonied Protozoans. 
Reproduction in Vorticella and in such colonied forms as 

Gonium, Pandorina, and Volvox. 
General characteristics and classification of Protozoans. 

5i 



52 PORIFERA 

GRANTIA, A CALCAREOUS SPONGE 

(Optional) 

Grantia is one of the simplest sponges. Compare several 
specimens and describe color, shape, and size. 

Is it divided into dorsal and ventral, right and left, anterior 
and posterior parts ? Is it bilaterally symmetrical ? 

How do the two ends differ ? Can you see evidence of 
attachment ? 

Examine the outer end with a lens. Look for an opening, 
the osculum. The needlelike fringe surrounding it con- 
sists of limy spicules. 

Examine the surface of the body carefully. Is it smooth ? 
Can you see any other spicules ? 

Look for other openings, inhalent pores. Are they numer- 
ous ? 

Draw a sponge ( x 10). 

Cut a specimen in half lengthwise and look for a body 
cavity, the cloaca. What shape ? What is its outlet ? 

Examine its walls. How are they marked off ? 

Can you make out pores ? These are called ostia. 

In the substance of the body find radial canals connecting 
the inhalent pores and the ostia. 

Water enters the inhalent pores and is ejected through the 
osculum. What is its course ? 

Examine specimens for young sponges budding from the 
larger ones. Where do the buds form ? 

Examine some sponge spicules with 1. p. and then with 
h. p. How many different kinds can you find ? 

The needlelike spicules form around the pores ; the others, 
imbedded in the flesh of the sponge, form a skeleton. 

Draw the dissected sponge (x 10) to show radial canals, 
ostia, etc. Draw spicules as seen under the lens. 



THE COMMERCIAL SPONGE 53 

THE COMMERCIAL SPONGE 

The animal whose skeleton we know as the sponge of com- 
merce is much more complex. 

What qualities make the household sponge valuable ? 

Compare a wet sponge with one that is dry. 

Select a specimen that has large pores which do not com- 
pletely perforate the sponge. Probe the larger pores 
with some slender blunt instrument. Do they communi- 
cate with each other directly ? Hunt for smaller pores. 

Examine a sponge that has been cut in two through one of 
the large pores. Look for grooves on the surface and 
for tubes running parallel to the surface. How many 
classes of tubes or pores have you found ? 

Examine some fibers of this sponge and compare with the 
spicules of Grantia. What differences have you found 
between Grantia and the commercial sponge ? 

Sponges reproduce, not only by budding, but also by eggs. 
Certain cells in the mesoderm become ova. Certain other 
cells divide into a number of active sperms. The sperm 
fertilizes an ovum and forms an oosperm, which remains 
imbedded in the mesoderm close to a pore until it reaches 
the blastula stage. Then the cells of half the blastula 
become ciliated and the young sponge, freeing itself from 
the surrounding tissue, escapes into the pore and out 
through the osculum, to float about till the gastrula stage 
is reached. Then it settles on the sea bottom to develop 
a form like the parent. 

Advanced Work. Topics suggested for further investi- 
gation, reading, and discussion : 

Examination of a fresh-water sponge. 

Glass sponge skeleton. 

Methods of obtaining and preparing sponges for market. 



THE FRESH-WATER HYDRA 

Alcoholic Specimens. 

Naked eye characteristics : Shape ? Color ? Size ? 

At one end note the tentacles. Examine with a lens. 

How many ? The mouth opening is between them. 

Make a drawing of your specimen (x 5) and mark parts. 
Microscopic features : Examine with 1. p. the tentacles. 

Note the lasso cells dotting the surface. Describe their 

appearance and arrangement. 
Examine a cross section with 1. p. Note the central or 

gastric cavity surrounded by the body wall. Of how 

many layers does the latter consist? The outer is called 

ectoderm ; the inner, endoderm. 
Can you see a supporting layer between them ? Is this 

divided into cells ? 
How do ectoderm and endoderm differ ? 
Draw (x 5) and mark ectoderm, endoderm, supporting 

layer, and gastric cavity. 
Examine a longitudinal layer and identify the same fea- 
tures. Draw ( X 5) and mark parts. 
Examine a specimen that is budding. Where on the body 

is the bud formed ? Is the cavity of the bud connected 

with that of the parent body ? 

Sexual Reproduction. 

Look for slight elevations on the sides of the body. Can 
you see any near the base ? If so, what shape ? These 
are ovaries, and each contains a single ovum. 

Are there any elevations near the mouth ? If so, what 
shape ? These are spermaries, from which are dis- 
charged numerous sperms that swim actively in the 

54 



THE FRESH-WATER HYDRA 55 

water. When one of these sperms enters the ovary of 
another hydra, it fertilizes the ovum and forms an 
oosperm. 
Segmentation then begins and after a small mass of cells 
is formed it becomes covered with a layer of tough pro- 
tective cells. The young embryo then breaks away and 
drops to the bottom, where it lies quiet for a time and then 
completes its development into a form like the parent. 

The Live Hydra. 

Examine Hydras in an aquarium and note the movement 
of the tentacles. For what purpose used ? In what 
ways is locomotion effected ? 

Arrange the aquarium so that one end will be in a strong 
light and the other in the shade. What happens ? Is 
Hydra sensitive to light? 

Touch a tentacle with a pencil. What conclusions do you 
draw ? 

What is the food of Hydra ? Try feeding one with bits of 
water plant and meat, or with small crustaceans. How 
is its prey captured ? Where digested ? 

Has Hydra any respiratory, circulatory, or excretory or- 
gans ? How are these functions of the body performed ? 

Where are Hydras found ? They are prey of other, larger 
animals, especially some species of pond snails. Why 
are they not found in all fresh-water ponds ? 

A CAMPANULARIAN HYDROID 

(Optional) 

Notice the slender branching stem with its rootlike base 
for attachment to some support, and the hydralike buds, 
hydranths or zooids. Look near the base for other vase- 
like buds without tentacles. These are gonangia. 



56 CCELENTERATA 

Examine a branch with 1. p. and notice the perisarc, a 
transparent chitinous sheath covering the stem. Does 
it also cover the hydranth ? 

Within the perisarc is a hollow tube of the same layers as 
in Hydra, and the hydranths are buds that, instead of 
becoming free as in Hydra, remain attached to the par- 
ent. Examine a hydranth carefully and compare its 
structure with that of Hydra. How do they resemble 
each other and how do they differ ? 

Since the hydranths are connected by a hollow stalk whose 
endodermal cells are ciliated, food and water circulate 
freely through the colony. 

Examine a gonangium with 1. p. and h. p. Identify the 
perisarc and a slender hollow axis bearing medusa buds. 
These medusa buds escape from the gonangium to be- 
come free-swimming. 

Make a drawing of the whole colony ; of a hydranth ; and 
of a gonangium enlarged to show all features. 

Examine a medusa from one of the colonies. Of what 
sort of material does the body consist ? What is its 
shape ? 

The convex surface is called the exumbrella, the other 
the subumbrella. Are there tentacles ? If so, where 
and how many ? 

Find the proboscis at the end of which is the mouth. 
Locate it. It contains part of the stomach. 

Make out four radial canals extending from the stomach 
to a circular canal near the edge of the umbrella. 

Examine the edge of the umbrella and notice extending 
from it a shelf-like velum. 

Among the bases of the tentacles look for marginal sense 
organs. How many ? These are probably balancing 



THE FRESH-WATER HYDRA 57 

Find on the subumbrella side of the body, four reproduc- 
tive organs containing either ova or sperms. A sperm 
from a male medusa finds it way to the ovary of a fe- 
male and, entering, fertilizes the ovum. The oosperm 
develops into a free-swimming embryo which finally 
settles down, and by budding builds up a colony which 
resembles the grandparent. 

Thus every other generation is a colonied form. Its re- 
production is by what process ? 

What sort of reproduction has the alternate jellyfish 
generation ? 

Of what advantage to the colony to have every other gen- 
eration a free-swimming form ? 

THE SEA ANEMONE 

(Optional) 

Compare the shape of the body of a sea anemone with that 

of Hydra. Locate the mouth. What is its shape? 

How is it surrounded ? Describe the arrangement of 

the tentacles. 
Examine a section of the body cut across near the top. 

Identify an outer wall. Of what cell layers composed ? 

Is there a supporting layer ? 
Identify a central cavity, the stomach. This is an infold- 
ing of the outer wall. Which layer is ectoderm and 

which endoderm ? 
How are stomach and body wall connected ? How many 

spaces are separated by these primary partitions, or 

septae ? 
Are there any other partitions besides the primary ? How 

are they arranged ? 
Make a drawing to show this arrangement of parts. 



58 COELENTERATA 

Examine a longitudinal section of the body taken through ' 
the center of mouth and stomach. Does the latter ex- 
tend to the base of the body ? Is it closed at the lower 
end ? How can digested food and oxygen reach all 
parts of the body ? 

A STAR CORAL 

Examine the skeleton. Of what substance composed ? 

Examine the skeleton of a single polyp. Can you see any 
relationship between its plan and that of the sea anem- 
one ? This skeleton was formed between ectoderm and 
endoderm. 

Has the body of the sea anemone any such supporting 
layer ? 

Did the skeleton of the coral polyp extend into its stom- 
ach ? Into the tentacles ? 

Is it heaviest in walls, base, or partitions ? 

Compare a branching coral with the Campanularian hy- 
droids. 

Corals have no alternate generation. 



THE STARFISH 

(Optional) 

Alcoholic Specimens. Dorsal Side. 

How many rays and how arranged ? Is the surface con- 
cave or convex ? Examine the skin. Is it thin or 
leathery ? Smooth ? 

Look for spines. Are they movable ? 

Look for small elevations between the spines. What do 
they resemble ? They are breathing organs. 

Find a wartlike, light-colored elevation on the central 
disk — the madreporic plate. Locate and describe it. 

The ray opposite is the anterior ray. 

Bend a ray to test its flexibility. Search with a lens for a 
red or yellow eye spot on the end of the ray. 

Find a tentacle, the organ of smell, just above it. 

Find a tiny hole near the center of the disk, the anus, or 
outlet of the intestine. 

Draw a dorsal view and mark madreporic plate, anterior 
ray, eye spot, organ of smell, and anus. 

Ventral Side. 

Find the mouth. Where ? By what surrounded ? This 

is the peristome. 
Note the furrow along the center of each ray. Look for 

four rows of tube feet. Describe their arrangement. 

Examine a specimen whose water vascular system has 

been injected to see these more clearly. 
Note the spines. Are they movable? Locate them. 

How do they compare in size with the other spines ? 

59 



60 ECHINODERMATA 

Draw a ventral view of the central disk and anterior ray 
and mark the mouth, furrow, tube feet, and movable 
spines. 

Dissection. 

Find the anterior ray and with scissors cut a slit across the 
dorsal side near the tip. 

Insert the point of the scissors and cut the dorsal wall 
along the edge on each side to the angle of the rays, 
being careful not to cut anything but the body wall. 

Turn back the loose piece and see, fastened to its under 
surface, a double gland, the " liver," held in place by a 
delicate membrane, the mesentery. 

Its secretions can digest starch, fat, and albumen. To 
what organ in the human body does it most nearly cor- 
respond ? 

Examine the floor of the ray. Notice the ridge corre- 
sponding internally to the external furrow. 

Look for membranous sacs, the ampullae, each connected 
with a tube foot. An injected specimen will show these 
more clearly also. 

Remove the " liver " from the anterior ray, cut off a piece 
of the dorsal wall, and examine for tiny flat plates im- 
bedded in the skin. Compare them with the plates in 
the ventral wall. 

Look for depressions in the dorsal wall between the plates. 
To what on the outside do they correspond ? 

Above what are the spines fastened ? 

Bend the ventral surface to see the furrow more plainly. 

Find a nerve cord running along the center to the end of 
the ray. With what does it connect there ? 

Trace it back towards the mouth. It connects with a ring 
around the mouth. 



THE STARFISH * 6l 

Cut across the ray and find in the furrow just above the 
nerve cord a tiny hole. You have cut a tube that carries 
water to fill the ampullae, which in turn fill the tube feet. 

Next cut loose the dorsal wall of the ray on each side of 
the anterior one, following the same method as with the 
anterior ray. Connect the cuts at the angles between 
the rays. 

Gently lift the central disk so as to expose the stomach. 
Note its five-lobed arrangement. 

Find in each ray two tiny, clear, threadlike muscles which 
run from the exterior of the stomach. Where is the 
other end of each attached ? These aid in the protrusion 
from the mouth of the lower part of the stomach. 

Note at the angles of the rays, close to the " liver, " the 
reproductive organs. Describe their appearance. These 
open by ducts whose tiny outlets are upon the dorsal 
disk close to the angles between the rays. 

The sexes are distinct, but ovaries and spermaries are so 
much alike that they can be distinguished only by careful 
microscopic examination. 

Look for the ducts leading from the " livers." They empty 
into the pyloric sac of the stomach. 

Above this is the intestine. Describe it. 

Cut across this and remove the stomach. 

Cut off the dorsal disk except the portion around the 
madreporic plate. Note leading down from this a 
whitish tube. What letter does it resemble ? This is 
the stone canal. 

Find its connection with a circular tube around the mouth. 
Leading from this are the radial vessels which fill the 
ampullae. 

Examine an injected specimen for these parts. 

Trace the course of the water in this water vascular system. 



62 ECHINODERMATA 

Also connecting with the circular vessel, there is in each 
ray a pair of organs, whose function is the formation of 
white corpuscles or blood cells. 

Close to the " stone canal " find a muscular bulb, the 
" heart " of some authorities. 

This connects at each end with a circular vessel which in 
turn connects with other vessels and other organs. There 
is some difference of opinion in regard to these parts 
and their functions. 

The space between the organs of the starfish and its body 
walls is filled with a fluid, principally sea water, in which 
are white blood corpuscles. These are also found in the 
water vascular system. 

THE SEA URCHIN 

(Optional) 

Describe its shape. In what respects does its body cover- 
ing resemble that of the starfish ? How do they differ ? 

Locate the mouth. How many teeth ? How arranged ? 

What difference must there be between the food of the 
sea urchin and that of a starfish ? 

Locate the madreporic plate. 

Examining a skeleton, look for elevations upon which the 
spines articulated. 

Holding it to the light and looking in at the mouth open- 
ing, locate rows of tiny holes. These are apertures 
through which the tube feet protruded. How many 
sets and how many rows in each ? 

How does the sea urchin compare with a starfish in this 
respect ? 

Does a sea urchin show any signs of radial symmetry ? 

Why is it classed in the same branch but in a different class 
from the starfish ? 



THE SEA URCHIN 63 

Advanced Work. Topics suggested for further study 

and discussion : 
Food of starfish and methods of feeding, and economic 

relation of starfish to the oyster industry. 
Power of regenerating lost parts. 
Brittle stars, sand dollars, etc. 
The sea cucumber. 

The crinoid (both fossil and alcoholic specimens). 
General characteristics of branch as shown by forms 

studied. 



THE EARTHWORM 

The Live Animal. 

What is the shape of the earthworm's body ? 

Identify anterior and posterior ends. How can you tell 
which is anterior in any animal ? 

Is there any difference in shape between anterior and pos- 
terior in the earthworm ? Of what advantage ? 

Notice the division into segments, or somites. Is any part 
of the bodv not segmented? 

Has a worm distinct dorsal and ventral surfaces ? 

Can you see any difference in color ? In shape ? In mark- 
ing ? 

Draw it through your fingers and see if you can feel any 
difference. If so, to what due ? 

Has an earthworm right and left sides? How can you 
determine right and left for any animal ? What kind of 
symmetry has an earthworm ? 

Describe the color. Would any other color do as well ? 
Explain. Xote the iridescence of the skin. 

Watch an earthworm crawling. Describe the changes in 
the shape. 

Does the whole bodv move at once ? 

There are two sets of muscles concerned in this movement. 
When the body shortens, are circular or longitudinal 
muscles contracting ? * Which set must contract to 
lengthen the bodv ? 

Observe a dorsal blood vessel. Does it pulsate ? Can you 
tell in which direction it carries blood ? 

64 



THE EARTHWORM 65 

What color is this blood ? Can you see a ventral vessel ? 
Hold the worm in the light and notice dark food masses in 
the alimentary canal. 

Special Senses. 

Using a toothpick, determine which part of the body has 

the keenest sense of touch. 
Dip a toothpick in sugar solution, move it towards the 

anterior end, being careful not to touch it, and see if 

the earthworm shows any sense of smell. 
Repeat with beef extract. Try other substances, but be 

careful not to use any irritating substance. Why ? Does 

the worm distinguish between odors ? 
Put the worm in a test tube, and covering one half of the 

tube to darken it, decide whether any part of the body 

is sensitive to light. If so, which ? 
Take a lens and focus the light along the body, beginning 

with the tail. Does the result coincide with the pre- 
ceding ? 
Place the worm on a paper, part of which is damp and 

part dry. Does the worm prefer damp or dry places ? 
With the breath blow upon the worm. Fan it or blow 

with a tube. Is it sensitive to a breeze ? 

Habits and Environment. (Field work) 

Where do earthworms live ? How can you recognize their 

burrows ? " 
How deep do they go ? Does temperature affect this 

depth ? 
In what kind of soil most numerous ? Why ? 
Why do we see so many after a rain ? 
Do we usually see them on the surface of the ground ? 

Explain. At what time might we find them ? 

LAB. MAN. ZOOL. — 5 



65 VERMES 

External Features of Alcoholic Specimens. 

Examine more carefully the segments of the body. Notice 

folds in the skin apparently doubling the number of 

segments. Can you suggest a use ? 
Count the segments in your specimen and compare the 

number with that in several others. Is it always the 

same ? 
Look for the mouth. In front of it find the lip. How 

arranged ? 
At the posterior end of the body find the anus. 
A short distance from the anterior end note the clitellum, 

a thickening of the body. Is it found on all specimens ? 

Is its location the same whenever found ? It is developed 
> only on full-grown worms and secretes upon its surface 

a viscid fluid which envelops the eggs and hardens into 

a capsule for their protection. 
Examine with a lens for tiny bristles called setae. How 

many on each segment ? Location and arrangement ? 

Does every segment bear them ? What is their use ? 
Look with the lens for the openings of ducts from the 

reproductive organs. 
The oviducts open on the 14th and the vas deferens or 

spermiducts on the 15th segment. 

Cross Sections. 

Examine a cross section and note cuticle, muscular body 
wall, body cavity, and alimentary canal. 

Examine a slide showing same, and note again the same 
structures, identifying the two sets of muscles. 

Note the extension or infolding of the dorsal wall of the 
intestine, diminishing the space but increasing the sur- 
face of the lining. 

Make a drawing and mark all parts. 



THE EARTHWORM 6j 

Internal Organs. (Optional) 

With scissors cut the skin of a specimen along the median 

dorsal line, lay it in a dissecting pan, and pin the skin 

back to show the internal organs. 
Note the parts of the alimentary canal. 

a. The pharynx, in segments 2-6 inclusive. 

b. The narrow esophagus, hidden by other organs. 

c. The soft-walled crop, in the 14th or 15th segment. 

d. The hard-walled and white gizzard, in segments 17, 18, 
and 19. 

e. The stomach-intestine, which runs through the rest of 
the body. Is it of uniform diameter ? Describe it. 

Above the pharynx find the cerebral ganglion. Describe 
it. Can you find connecting with it a nerve cord en- 
circling the pharynx ? 

Above the intestines note the dorsal blood vessel. 

In segments 10-13 n °te the whitish reproductive organs, 
the sperm sacs. 

In segments 7-1 1 see also the red aortic arches connecting 
the dorsal and ventral blood vessels. 

How is the alimentary canal held in place ? Are there 
any internal features corresponding to the external seg- 
ments ? 

Make a drawing to show the alimentary canal and mark 
its parts. 

Remove the organs observed and look for the ventral 
blood vessel. 

Find in the 13th segment the small ovaries. What 
shape ? 

Look for the ventral nerve cord. Has it any ganglia ? If 
so, how many ? How are they located ? 

Can you see any branches ? Where are they given 

off? 



68 VERMES 

Find on the ventral body wall small glands, threadlike and 
coiled. How many ? These are organs of excretion. 
To what organ in man do they correspond ? 

They open by tiny pores on the ventral surface, a pair to 
each segment. 

Trace the nerve cord forward to the anterior region. It 
connects by means of the circular collar with the cere- 
bral ganglion. 

Make a diagram of the nervous system and mark its parts. 

THE LEECH 

(Optional) 

In what respects does its form resemble that of the earth- 
worm ? How do they differ ? 

What adaptations to its environment and mode of life can 
you find ? 

Look for five pairs of eyes and locate them. 

Locate and describe the mouth. 

Locate the anus. 



THE SANDWORM (NEREIS) 

(Optional) 

Compare with the earthworm. 

How can you distinguish anterior from posterior? Dorsal 

from ventral ? 
Look for eyes. How many and how located ? 
What is the arrangement of the appendages ? Does every 

segment bear a pair ? They are called parapodia. 
Cut off and examine one with a lens. The larger fleshy 

portion is a gill ; the tuft of hairlike bristles are setae. 



THE SANDWORM 69 

Which is the dorsal part of the parapodium ? 

The sandworm has tentacles and palpi. How many pairs 
of each ? Locate them. 

Slit open the eight anterior segments and find the large 
proboscis, which is capable of being reversed and pro- 
truded. 

Find a pair of jaws. Is the sandworm herbivorous or 
carnivorous ? 

Advanced Work. Topics suggested for further study 
and discussion : 

Life history of the earthworm and its economic importance. 

Flatworms: Planarians and tapeworm. 

Roundworms : vinegar eel, trichina, Gordius. 

Rotifers. 

Parasitism and degeneration. 



THE FRESH-WATER MUSSEL 

The Shell. 

How many pieces has the shell ? Each is called a valve, 

and the animal is a bivalve. 
Note the leathery elastic ligament joining the valves at 

the hinge. 
Identify lines of growth marking successive additions to the 

shell. The point around which they center is called the 

beak, or umbo. This points toward the anterior margin. 
The animal moves by means of a fleshy lobe, the foot, 

thrust out of the anterior margin. Is the hinge dorsal 

or ventral ? 
Note the epidermis covering the shell and giving its color. 

If this is removed, what substance is exposed ? 
The composition of the shell ? Test a piece in dilute HC1, 

for twenty-four hours. Does anything remain ? If so, of 

what character ? What substance was dissolved by the 

acid ? 
Roast a shell in a bed of hot coals and break in halves 

from ventral to dorsal margin. Examine the layers of 

which it was composed. How arranged ? 
Draw the exterior of the right valve with the dorsal side 

up and mark beak, hinge, dorsal and ventral margins, 

and lines of growth. 
Examine the interior of the shell. Note the pearly nacre 

lining it. Is its color the same in all shells ? 
Examine the prominences near the hinge, the teeth. Their 

use ? What two kinds ? Position of each ? Are they 

alike in both valves ? Of what use ? 

70 



THE FRESH-WATER MUSSEL 7 1 

Identify two scars near the teeth, the anterior and posterior 
adductor muscle scars. Each marks the attachment of 
a muscle which joins the valves. Of what use is this ? 

What would open the shell ? 

Note the pallia! line parallel with the edge of the shell. 
Where does it begin and where does it end ? 

Draw the interior of the right valve and mark teeth, muscle 
scars, and pallial line. 

The Live Mussel. 

Put about three inches of sand in a tub or aquarium and 

cover with three inches of water. When this is clear, 

drop gently into it several mussels and note carefully 

the position of each. At the end of twenty-four hours 

observe their positions. 
If the shells have opened, look for any protruding parts. 

Locate and describe each. 
When a mussel is lying with shell slightly open and hinge 

up, is anterior or posterior end more exposed ? 
Can you see two elliptical openings ? These are siphons. 
Diminish the water till it barely covers the siphons, and 

watch the surface of the water for currents. Can you 

see any ? 
With a dropper gently introduce a little coloring matter 

close to the siphons and determine the currents. 
Use sugar solution and then vinegar. What happens ? 

What do you conclude from this ? 
If a mussel can be seen moving, study the action of the 

foot and the position of the shell. Is the movement 

regular ? 

Internal Organs. 

Examine animals whose shells have been opened. What 
muscles were cut in order to open them ? 



72 MOLLUSCA 

Note the body covering, or mantle. Each half is a lobe or 
leaflet. Note its loose edge. What relation to the pal- 
lial line ? 

Note the siphons. Where located ? How formed ? How 
bordered ? 

Through which does water enter ? This is called the 
incurrent siphon ; the other is the excurrent. 

Identify the foot. Where located ? 

Back of this, between the mantle lobes, observe the gills. 
Where located ? How many leaflets ? Describe their 
appearance. 

With a knife scrape a gill gently, and mount the cells thus 
removed for examination with h. p. Observe the vibrat- 
ing cilia which cover the surface of the gills. 

In front of the gills find the triangular labial palpi. 

Lift the mantle lobe and see that the two inner gills unite 
to inclose a channel leading into the excurrent siphon. 

Look for the mouth opening below and behind the anterior 
adductor muscle. What surrounds it ? 

What sort of food must the mussel take ? How does it 
reach the mouth ? 

THE OYSTER 

Compare the oyster shell with that of the river mussel. 

Which is equivalved and which unequivalved ? Identify 

lines of growth, beak, hinge, and right and left yalves. 
Is the ligament external or internal? How does it work? 
Is the hinge on a long or short edge of the valve ? Does 

it differ in any other respects ? 
Examine the interior. Can you see any teeth ? Can you 

explain why the oyster and mussel shells differ in this 

respect ? 
The black spot is an adductor muscle scar. Why does the 



THE SNAIL 73 

oyster need but one adductor muscle, while the river 
mussel has two ? 

Is there any pallial line ? 

Examine an oyster whose shell has just been opened, and 
identify mantle lobes and gills. 

Is there any foot ? 

Are siphons present ? 

What differences in the habits and environment of the 
mussel and the oyster will account for differences be- 
tween the animals and between their shells ? 

Draw exterior and interior of right valve. 

THE SNAIL 
The Shell. 

Why called univalve? Identify the point or apex. The 

turns are called whorls. How arranged ? 
The joint between the whorls is the suture. 
How are the lines of growth arranged in relation to it ? 
The opening is the mouth, or aperture ; and the free edge, 

the lip, or peristome. Is it thin, thickened, or reflected ? 
Look for teeth, prominences either on the body whorl or 

on the peristome. How many and where located ? Can 

you think of any possible use ? 
Determine whether the shell is dextral or sinistral by 

holding with apex up and aperture towards you. If the 

peristome is to the right, the shell is dextral; if to the left, 

sinistral. 
The central point of the under side is the umbilicus. Is it 

open or closed ? 
Compare several species of shell. In what respects do 

they differ ? 
Make drawings of the shell as seen from above, from below, 

and from the side, and mark all features shown. 



74 MOLLUSCA 

The Live Snail. 

Examine one that is crawling. 

All that part of the body used for locomotion is called the 

foot. 
Locate the head, mouth, and tentacles. How many tenta- 
cles ? 
Examine with a lens. Upon which pair are the eyes ? 
Touch the eye. What happens ? Is its sight acute ? 

How can you tell ? 
Put the snail on a piece of glass and from below watch its 

crawling. Describe its movement. 
Does it ever crawl backwards ? 
Is it attached closely to the shell? 
Try feeding snails with various kinds of green stuffs such 

as lettuce or cabbage, and also moistened bread and cake 

crumbs. 
How does it use its tongue ? Has it a sense of taste ? 
Test also for smell. Is that developed ? 
Look near the peristome for a breathing pore. Does it 

open and close with any regularity ? 
Examine a slug. In what respects does it resemble and 

in what differ from the snail ? 
Why are river mussels, clams, oysters, snails, and slugs, 

classed together as Mollusks ? 
Why are the first three in one Class and snails and slugs in 

another ? 
Why are the mussel and oyster placed in different Orders ? 

Advanced Work. Topics suggested for further study 

and discussion : 
The squid, cuttlefish, octopus, argonaut, and nautilus. 
The economic importance of mollusks. 
Fossil forms. 



THE GRASSHOPPER 
Alcoholic Specimen. 

What is its general shape ? 

How does its form differ from that of the crawfish, and of 
what advantage to each animal is the build of its own 
body ? 

Describe its coloring. Of what advantage ? 

Describe the body covering. It consists of chitin. 

Compare with the crust of the crawfish. What advantages 
to each animal in the character of the covering, or what 
disadvantages would they suffer if the skeletons were 
exchanged ? 

Of what three great regions does the body consist ? 

Which two are more distinctly separated than in the craw- 
fish ? 

Which parts of the body show segmentation distinctly ? 

The Head. 

What shape ? Is there any neck ? 

In what direction does the head move most freely and 

what advantage is gained by this movement ? 
Note the antennae. Are they segmented ? 
Note a pair of eyes. Examine with a lens. Are they 

simple or compound ? 
Find three small simple eyes — the ocelli. Locate them in 

relation to other parts. 
Draw a front and a side view of the head, showing these 

parts, and designate them. 

75 



76 ARTHROPODA 

The Thorax. 

Identify three segments : prothorax, mesothorax, and 
metathorax. 

What paired appendages on each ? 

What is the shape of the prothorax ? 

Examine the outer wings. To which segment are they 

fastened? What is their resting position ? 
Why is the order to which the grasshopper belongs called 

" straight-winged " (Orthoptera)} 
Spread the outer wings and examine the inner or hinder 

pair. How folded when at rest? 
Compare the fore and hind wings as to shape, size, and 

thickness. Note the veins in the hind wings. Where 

heaviest ? How arranged ? 
Are the wings fastened to the body nearer to the dorsal 

or the ventral side ? Why? 
What is the function of the fore wing ? A wing used for 

protection is called an elytron. 
What is the use of the hind wing ? To what segment 

fastened ? 
How are strength, lightness, and size secured together ? 
Why is it more necessary to a grasshopper .to have a wing 

that will fold than it would be to a butterfly ? 
Draw a fore and a hind wing fully spread and put in the 

principal veins. 
Examine the legs. What position has each pair in relation 

to the body ? 
Compare the size. 
Of what advantage to have the hinder pair so different in 

structure and position from the others ? 
Observe three principal parts of a leg : the femur, or upper ; 

the tibia, or middle ; and the tarsus, or foot. Which is 

the heaviest ? 



THE GRASSHOPPER 77 

Examine the tarsus with a lens and observe its jointed 

structure. 
Can you suggest uses for hooks and pads ? For the 

spines on the hind tibia? 
Draw a dorsal view of the grasshopper with the wings 
- folded ; a side view to show the legs. 
Remove the legs on the right side and draw each. 

The Abdomen. 

Of how many segments does it consist ? (The first and 

last are incomplete.) 
At the end of the abdomen of the female look for two 

pairs of wedge-shaped organs which form an ovipositor, 

or egg placer. 
Look on the sides of the abdomen for holes called spira- 
cles. How many on each segment? 
Look for a pair on the metathorax and one below the 

hinder edge of the prothorax. Does every segment 

have them ? 
How many in all ? 

These openings are breathing pores. 
They communicate with tubes called tracheae, which send 

branches all through the body and carry air even into 

the legs and wings. They also fill and empty air sacs. 
Examine a slide showing a spiracle of some insect. How 

is the opening guarded? How is dust sifted out? 
Examine a slide showing tracheae. 
In order that oxygen and carbon dioxide may be exchanged 

through their walls, what must be their character ? 
How is strength secured ? 
Could you drown a grasshopper by immersing its head in 

water ? 
Look on the first segment of the abdomen for ear sacs. 



?8 ARTHROPODA 

Draw a side view of the abdomen to show these parts. 
Examine the mouth parts. The upper lip is the labrum ; 

the lower, the labium. Describe each as to shape and 

position. 
Are the lips movable? What is their function ? 
The jointed appendages of the labium are palpi. 
Remove labium and labrum and draw (x 5). 
Examine the inner surface of the labrum for taste cups. 
Examine the mandibles, or jaws. Describe them. 
In what direction does the mouth open between them? 
Observe the maxillas. Their appendages are also palpi. 
What is the function of the jaws ? Is the mouth adapted 

to liquid food ? 
Draw mandibles and maxillae ( X 5). 

The Live Insect. (Field work) 

Where should you look for grasshoppers ? Do they prefer 
woods or field ? 

Try to catch one. Does it escape by flying or jumping ? 

How many times its own length can it jump ? 

Can a grasshopper hear ? Give reasons for thinking as 
you do. The sound which it makes is produced by 
rubbing parts of the body together. 

Capture a grasshopper and put it, with some leaves on 
which it can feed, in a jar or box, covering that closely 
with netting. What is the position of each pair of legs 
when at rest ? Try feeding it various vegetable foods, 
such as lettuce, cabbage, and slices of apple and potato. 
Has it a sense of taste ? 

Watch it while it is eating to see the movements and use 
of the different mouth parts. 

What is the color of the fluid in the mouth ? 

What other use has this besides digestion ? 



THE GRASSHOPPER 79 

Test for a sense of smell. How can you do this ? What 
must be guarded against ? 

Test the sense of touch. What parts are most sensi- 
tive ? 

Watch the abdomen for movements. These are concerned 
in respiration. 

Find specimens whose wings are small or undeveloped. 

These are the young. 

Like the crawfish, the grasshopper molts or sheds its 
skeleton. Why ? In what other respects does the 
grasshopper resemble a crawfish ? 

How do they differ ? 

Why are they classed in the same branch but in different 
classes ? 

Advanced Work. Topics for further study and discus- 
sion: 

Reproduction. 

Locust scourge and migration ; methods suggested for 
extermination ; work of government in Agricultural 
Department. 

Locusts as food. 

Other members of the order. 

THE CECROPIA MOTH 

(Optional) 

Identify head, thorax, and abdomen. 

Compare the general shape with that of the grasshopper. 

Has the thorax the same number of segments and append- 
ages as the thorax of the grasshopper ? 

Compare fore and hind wing with those of the grass- 
hopper. 

What difference in the use of each in the two insects? 



80 ARTHROPODA 

What difference in their resting positions ? 

Examine the legs. Has each a femur, tibia, and tarsus ? 

Are the legs as well developed as in the grasshopper? 

What differences in use will account for differences in 

development ? 
Examine a bit of wing under 1. p. Note the scales. How 

arranged ? How attached ? 
Draw a bit of wing to show this. 
Scrape off a few scales and examine with h. p. Draw to 

show the shape. 
Examine a bit of wing from which the scales have been 

removed. What is its character ? 
Compare the antennae of the moth with those of the grass- 
hopper. 
Compare the antennae of several Cecropia moths. Are 

they all relatively as large and feathery ? Those of a 

male are larger in proportion than those of a female. 

Identify male and female by the antennae. 
Compare the main divisions of the body in the two sexes 

as to size and shape. How do they differ? 
Note the size and position of the eyes and compare with 

those of the grasshopper. 
Examine the mouth parts. The coiled sucking tube 

consists of modified maxillae, which, being grooved on 

their opposed surfaces, form a channel for the nectar 

which is the food of this moth. 
The short feathery labial palpi are close to the sucking 

tube. 
Since a moth takes only liquid food, will it need a crop and 

gizzard ? 
Draw a dorsal view of a moth and indicate whether it is 

male or female. 



THE CECROPIA MOTH 8 1 

METAMORPHOSIS OF CECROPIA 

(Optional) 

Examine a moth's egg. If Cecropia eggs are not to be 
- had, the egg of the imported silkworm will do. Describe 

its color, size, and shape. What is its covering ? What 

sort of an animal is hatched from the egg ? This is 

called the larva. 
Examine a good-sized active larva. Is there a distinct 

head ? Are antennae present ? 
Identify labrum, labium, mandibles, and maxillae. How 

used ? 
What is the food of a larva ? Compare the character and 

amount of food taken in a day by the larva with that 

taken by the imago or winged form. 
Has the larva a distinct thorax ? How many segments has 

the thorax ? What marks them ? 
How many other pairs of legs has the larva? Where 

located? These are called prolegs to distinguish them 

from the true or thoracic legs. Can you discover any 

differences between them ? 
Count the segments of the abdomen. Is the number inva- 
riable ? 
Look for spiracles. How many and where ? 
Draw a side view of a full-grown larva. 
Watch a larva that is beginning to spin its cocoon. Of 

what material ? 
It is formed by the hardening of a secretion from glands. 

Where does the secretion seem to come from ? 
How is the cocoon held in place? 
Examine a Cecropia cocoon. What is its shape ? How 

was it securely suspended ? 
What is the character of the covering ? 

LAB. MAN. ZOdL. — 6 



82 ARTHROPODA 

If the moth has emerged, from which end did it escape ? 
Compare the size of the opening with the size of the 
moth's body. 

Could a moth bite its way out of the cocoon ? 

It has been found that when the moth is ready to emerge 
from its cocoon a small amount of strong alkali is ejected 
from its mouth, which cuts the silken threads and allows 
the insect to escape. 

Draw a cocoon. 

Examine one that has been cut open. Of how many layers 
composed ? How does the inner differ from the- outer ? 

The stage of the insect within the cocoon is called the pupa. 

Examine a Cecropia pupa. What color ? 

What is the character of the skeleton ? 

Can you distinguish head, thorax, and abdomen ? 

Examine the pupa skin. Can you see signs of wings ? 
Antennae ? Sucking tube ? 

Can you find spiracles ? 

Draw dorsal and side views of the pupa.' 

What are the stages in the life of a moth ? The series of 
changes from stage to stage constitute what is known 
as the metamorphosis of the insect ; and when the stages 
are clearly defined, the metamorphosis is said to be com- 
plete. Is it complete or incomplete in the grasshopper? 
In the Cecropia moth ? 

THE BUTTERFLY 

(Optional) 

Examine a butterfly. How does it differ from a moth in 
relative size and shape of parts ? In antennae ? 

If a live butterfly can be found, try feeding it with sirup 
or honey. To do this, hold it with the wings pressed 
together between the fingers of the left hand. 



THE HAWK MOTH 83 

With a needle uncoil the sucking tube, dip its end in the 

sirup, and watch the insect feed. 
Set it free in a breeding cage or screened room. What is 

the resting position of the wings ? 
Examine the larval or caterpillar stage of a butterfly. 

Does it differ in any essential particulars from that of 

the moth ? 
Examine the pupal stage. This is called the chrysalis. 
Is it protected by a cocoon ? How suspended ? 
Has a butterfly a complete metamorphosis ? 

THE HAWK MOTH 

(Optional) 
In the same way examine and compare the stages in the 

metamorphosis of a hawk or sphinx moth with those of 

Cecropia. 
In what respects do all three resemble the grasshopper ? 
These resemblances constitute the general characteristics 

of Insecta. 
In what respects do moths and butterflies resemble each 

other and differ from the grasshopper ? 
These points constitute the characteristics of the Order 

Lepidoptera, to which all butterflies and moths belong. 

OTHER WINGED INSECTS 

Examine a number of typical insects, and compare them 
in respect to the following points : 

a. Relative size, shape, and attachment of head, thorax, 
and abdomen. 

b. Character of fore and hind wings, and position during 
flight and when resting. 

c. Character and size of antennae. 

d. Development of legs and foot. 



84 ARTHROPODA 

e. Sting or ovipositor. 

f. Character and use of mouth parts as adapted for biting, 
piercing, sucking, etc. 

g. Character of larva and adaptation to its environment. 
h. Character of pupa. Active or quiet ? Protection ? 

i. Metamorphosis. Complete or incomplete ? 

THE SPIDER 

(Optional) 

Compare with grasshopper and crawfish as to the great 

divisions of the body. 
How many pairs of legs ? Where located ? 
Are antennae present ? Compound eyes ? 
How many simple eyes and how located ? 
Examine the mouth parts. Can you see the fangs, by 

means of which the spider pierces and poisons his victim ? 
Can you find the long pedipalps which act as antennae ? 
Examine the end of the abdomen for the spinnerets. 

Shape ? Number ? Location ? 
The silk is a secretion from numerous glands whose tubular 

openings are upon the spinnerets. 
Are young spiders very different from the parent ? 
Does the spider have any metamorphosis ? 

THE CENTIPED 

(Optional) 

Can you distinguish any head ? 

Are the thorax and abdomen distinct ? How many pairs 

of legs and how arranged ? 
Are there compound eyes ? Simple ? Antennae ? 
What mouth parts ? Is the food of the centiped solid or 

liquid ? 



THE CENTIPED 85 

This insect has a pair of poison glands which open on the 
fore feet. 

In what external respects do the spider and centiped re- 
semble other insects ? 

Internally they are all much alike in breathing and diges- 
tive organs, circulation, and the nervous system. 

In what important respects do the three Classes differ ? 
Why are they classed with the crawfish in the Branch 
Arthropoda ? 

Advanced Work. Topics suggested for investigation 

and discussion : 
Insects injurious to vegetation and methods recommended 

for their extermination. 
Beneficial insects. Cross-pollination by insects. 
Protective resemblance. Mimicry. 
Parasitism. 
Social organization. 



THE FROG 
A Vertebrate Type 

External Features. 

Examine a live animal. What is the general shape of the 
body ? 

Is there any neck? Any external division of the trunk 
into thorax and abdomen? 

Describe the texture of the body covering. Is it moist or 
dry ? 

Describe the coloring. How does it differ on dorsal and 
ventral surfaces ? Can you think of any advantages in 
each case ? 

Put a frog in the dark for a couple of hours, keeping an- 
other exposed to the light for the same period. Is the 
color affected by light ? If so, how, and of what advan- 
tage to the animal ? 

The Head. 

Of what shape ? Locate and describe the mouth opening. 
Are there any lips ? 

Look for nostrils. What is the character of the opening ? 

Examine the eyes. Describe them as to size and position. 
What is the shape of the pupil ? The color of the iris ? 

Touch one with the finger. What happens ? What ad- 
vantage in this ? 

How does the upper eyelid differ in structure and move- 
ment from the lower ? The latter is a nictitating mem- 
brane. 

Behind the eye find the drum membrane of the ear. 

86 



THE FROG 87 

The Trunk and Limbs. 

Describe the position and shape of the backbone when the 

frog is quiet. 
Compare fore and hind leg as to length. As to the length 

of the foot and the number and arrarfgement of the toes 

or digits. ' 
When the frog is at rest what is the position of the knee 

joint ? of the elbow ? of the ankle ? of the wrist ? 
Compare these with the position of the same joints in 

your own limbs when they are flexed. 
Is there any advantage to the frog in having its joints 

flexed when resting ? 
Watch a frog jump. How is the leap accomplished ? 
Put one in an aquarium and watch it swim. In what ways 

is the body adapted for this ? 
What resemblances are there between the frog, the dog, and 

man in the general plan of the body, the body covering, 

the limbs, and the number and location of the sense 

organs? What kind of symmetry do all three possess? 

Respiration. 

Study the breathing of a frog, watching the nostrils, 
throat, and chest. Compare the movements concerned 
in the frog's respiration with those of your own. How 
do they differ ? 

What two successive stages in a frog's inspiration ? How 
does each seem to be accomplished ? 

Prop the frog's mouth open. Can these breathing move- 
ments take place ? 

Special Senses. 

Test the frog's special senses. Has it keen sight? Hear- 
ing ? Smell ? Touch ? Taste ? Give reasons for your 
answers. 



88 VERTEBRATA 

Internal Features. 

Kill a frog with ether or chloroform. 1 Open its mouth 

and examine the interior. 
Notice the tongue. What shape ? Where attached ? In 

what position does it lie when not in use ? How is it 

used ? What assists it in catching prey ? 
Look for bristlelike teeth. Are they on both jaws ? Are 

there any others ? If so, where ? 
Open and close the jaws. Do both articulate with the 

skull by movable joints ? 
Look for the internal openings of the nostrils. Probe to 

find the passages. Locate them. 
Cut the drum membrane and probe the passage from the 

ear-cavity to the mouth. This is the Eustachian tube. 

Locate its inner opening. 
The rear part of the mouth constitutes the pharynx. In 

the floor of this, below the tip of the tongue, find the 

slitlike glottis through which air is forced into the 

trachea, or windpipe. 
Notice the connection of the pharynx with the esophagus. 

Dissection. 

Place the frog in a dissecting pan, ventral side up. Stretch 

the legs fully, and secure with pins through fore and 

hind feet. 
Cut the skin along the entire median ventral line, and 

make a second cut at right angles to this across its 

center. 
Is the skin closely applied to the flesh ? Can you push it 

away to expose the muscular wall beneath ? 

1 If the circulation of the blood in the webbing of the frog's foot was not 
examined in connection with the introductory studies in physiology, it should 
be done before killing the frog. (See page 41.) 



THE FROG 89 

Look for a dark vein on the median line, and cut through 

the body just to one side of this, being careful not to 

cut any of the internal organs. 
Continue this incision forward to the breastbone. Cut 

through the breastbone, also keeping a little to one side. 
Stretch the fore limbs to increase the width of the opening. 
Cut across the abdominal walls, at right angles to the 

former incision, and pin out the flaps. 
Keep the body covered with clear water. 

Abdominal Organs. 

Notice first the dark several-lobed liver. 

Lift its lower border and find the spherical gall bladder, 
connecting with the liver, and storing its secretion, the 
bile. Trace the bile duct to its union with the intestine. 

Push the liver aside and look for the stomach. 

By means of a tube inserted through the esophagus, blow 
into it and inflate it. Locate and describe it. 

What part of the alimentary canal follows the stomach ? 
What opening between ? (See page 26.) 

How is the intestine arranged ? What is its shape ? Its 
relative length and width ? 

Notice the division into small and large intestine. Why 
is each so called ? 

The enlargement close to the anus is the cloaca. 

Examine the membrane which holds the intestines, the 
mesentery. Move the organs about gently and discover 
how and where this is attached. 

What advantages are gained by this arrangement of the 
intestines in the mesentery ? 

In the first turn of the intestine in the folds of the mesen- 
tery find the pancreas. Describe it. Its secretion is 
called pancreatic juice. Where is it emptied ? 



90 VERTEBRATA 

Look also for the spleen, a dark body in the mesentery 
near the large intestine. Is it connected with the in- 
testine ? Describe it. 

Look on each side of the cloaca for a flat reddish kidney 
and a duct from each leading to a bilobed urinary bladder 
at the posterior end of the body cavity. What is the 
function of the kidney ? 

Near each kidney in the male frog is the whitish or yellow- 
ish spermary. What shape ? 

In the female the pair of lobed ovaries are similarly placed, 
but when distended by eggs they are very large and 
crowd the other organs. 

The oviducts are long convoluted whitish tubes which con- 
nect with the cloaca at one end and by a funnel-shaped 
opening with the body cavity above the stomach. 

Draw all the abdominal organs ( x 2). 

Lungs and Heart. 

Insert a tube into the glottis and inflate the lungs. Where 

are they ? What is their character ? 
While they are still inflated, tie a thread tightly around the 

base of each, cut them away, and allow them to dry. 

Then cut them open and examine their internal structure. 
Find, above and between the lobes of the liver, the heart. 

What color ? Shape ? In which direction does the apex 

point ? 
The membranous sac which incloses it is the pericardium. 

What is its character ? 
In a freshly killed frog the heart may still be beating. 

Time its pulsation. 
When the beating has ceased, warm it with the breath: 

What happens ? 
Prick with the forceps. Does it beat ? 



THE FROG 91 

Look for blood vessels connecting with it. The firmer 

ones are arteries, the soft, flabby ones are veins. What 

is meant by an artery ? A vein ? 
Remove the heart and examine its interior. The two 

upper cavities are auricles, the thicker-walled lower one 

is the ventricle. 
How are auricles separated ? 
What sort of opening between auricles and ventricle ? 

How guarded ? 
Look for a large vessel, the arterial bulb, arising from the 

ventricle. 

Circulation. (Optional) 

Examine a frog whose arteries have been injected. Into 
how many branches does the arterial bulb divide just 
above the heart ? 

Trace one of these to its division into three branches. The 
anterior or carotid artery sends two branches to the head. 

The posterior or pulmonary divides into two branches 
which supply the lungs and skin. 

The large middle artery, or aorta, curves to the dorsal 
region, and the right and left aortic arches unite in the 
middle line of the back to form a single dorsal aorta, 
which runs to the posterior along the median line, giving 
off branches to the various organs of the trunk, and then 
divides into two arteries, one to each leg. 

Find the median ventral vein which was seen in the body 
wall, and trace backward to see where branches enter it 
returning blood from the legs. How did the blood get 
from the arteries into the veins ? What exchanges took 
place during the course of this circulation ? 

Trace the median ventral vein forward to where, leaving 
the body wall, it descends to send branches to the lobes 
of the liver. 



92 VERTEBRATA 

Lift the organs that cover the kidney and find a vein com^ 

ing from the posterior end of the trunk and dividing into 

branches which enter the kidney. 
Find another set of veins coming from the kidneys and 

the various digestive organs and meeting in one large 

vein which runs to the liver. This is the portal vein. 

Draining the blood from stomach and intestines, what 

must it contain that was absorbed in those organs ? 
In the liver this blood runs through the capillaries there 

and comes in contact with the liver cells, which work 

several changes in it. 
What three vessels send blood to the liver ? Which brings 

a fresh supply of O ? Which a large supply of digested 

food ? Which C0 2 and other impurities ? 
Lifting the liver, find a vein running from it towards the 

heart. 
Lift the heart and look for two large veins bringing blood 

from the head and forward regions. These unite with 

the vein from the liver in the venous sinus, which 

empties into the right auricle. 
The blood from the capillaries of the lungs and skin is 

collected in pulmonary veins, which return it to the left 

auricle. 
Through which auricle does blood containing the larger 

amount of O flow? Through which that containing 

more C0 2 ? 

Nervous System. 

A. Spinal nerves. Removing the abdominal organs, ex- 
amine the interior of the dorsal wall for paired nerves 
lying against it. Where do they originate ? 

A union of several nerves forms a plexus. How many 
plexuses can you see ? 



THE FROG 93 

The posterior is the sciatic plexus, forming the sciatic 
nerve. What part of the body does it supply ? 

The anterior plexus is the brachial. What part is supplied 
by it ? 

B. Sympathetic system. Find if possible a delicate nerve 
cord lying close to the spinal column on one side, but 
ventral to it. 

Observe that this is slightly swollen at intervals into gan- 
glia, from which are given off branches to the internal 
organs and also to the spinal nerves on that side. 

Find a similar cord on the opposite side. Observe that 
the ganglia of the two cords are connected. 

This double chain of ganglia, with connecting nerves, is 
known as the sympathetic system, and largely controls the 
secretions and the work of the vital organs. 

C. The brain and cranial nerves. Turn the animal over and 
slit the skin along the entire median dorsal line. With a 
sharp knife carefully remove the top of the skull, and 
identify : 

(i) The two hemispheres of the cerebrum, elongated and 
white bodies in the anterior region of the brain. 

(2) Olfactory lobes, running forward one on each side of 
the hemispheres. In these the nerves of smell originate. 
What shape ? 

(3) Optic lobes, behind the hemispheres. Shape ? Relative 
size ? Find the optic nerve, connecting a lobe with an 
eye. 

Does the right lobe send its nerve to the right eye ? 

(4) The cerebellum, an unpaired and very small median 
dorsal division. 

(5) The medulla oblongata, extending backward from 
beneath the optic lobes and continuing in the spinal 
cord. 



94 VERTEBRATA 

Cutting away the backbone that covers it, trace the spinaj 
cord backward to its termination. What shape ? 

The brain, spinal cord, and connecting nerves constitute 
the cerebro-spinal system. 

Draw the brain and spinal cord as seen from above, and 
mark the parts. 

(Optional) 

D. Spinal cord. Examine with lens a slide showing a 
stained cross section of the spinal cord. (That of the 
human body or of any vertebrate animal will do.) Ob- 
serve dorsal and ventral grooves, or fissures. Into what 
parts do they nearly divide the cord ? 

Note the darker " gray matter." What letter does it 
resemble ? 

Examine with h. p. What microscopic structures does it 
contain ? 

Look at the surrounding " white matter." This consists 
of nerve fibers. 

Find the roots of a pair of spinal nerves. 

To what does the division of the nervous system into halves 
correspond ? 

Draw the cross section of the cord as seen under the lens. 

The Eye. (Optional) 

Notice the cornea, the glassy membrane over the front. 

Examine the sclerotic coat over the back. What color ? 

Note also the colored muscular iris, with its central open- 
ing, the pupil. 

Look for the dark choroid coat lining the eye, and for the 
crystalline lens which focuses the light. 

What is the nerve of sight ? Its ending in the eye is called 
the retina. On this the image is impressed. 



THE FROG 95 

Voluntary Muscles. (Optional) 

Skin one of the hind legs and study the arrangement of 
the muscles. What is the thick fleshy part of the mus- 
cle called ? (See page 44.) 

What fastens it to bone ? 

What covers it ? 

Pull apart the muscles on the upper leg or thigh and find 
the sciatic nerve. With scissors cut this as close to the 
trunk as possible. What happens ? 

Examine the muscle of the calf of the leg. Where is its 
. origin ? Its insertion ? 

The tendon of this end is the Achilles tendon. 

Mount a bit of muscle on a slide and examine with 1. p. 
and then h. p. Is it striated ? 

The Skeleton. (Optional) 

Examine a skeleton that has been carefully cleaned. 
(Mounted skeletons may be purchased of supply com- 
panies, but one may be cleaned by cutting away all 
soft tissues with sharp scissors. Be careful not to cut 
the joints. While you are working, keep the speci- 
men wet with water in which is a little alcohol. When 
the skeleton is clean, place it upon a dark card, bending 
the limbs into resting position. Prop with pieces of 
cork any parts which need supporting. Glue or sew the 
specimen to the cardboard.) 

Note the axial skeleton, consisting of the skull and verte- 
bral column ; and the appendicular, consisting of shoulder 
and pelvic girdles or arches and the attached limbs. 

Study the skull. Is the lower jaw directly attached to the 
cranium? Is there any other movable bone in the head? 

What is the character of the bones of the cranium ? 

Examine the backbone, or spinal column. 



96 VERTEBRATA 

The long piece at the end is the urostyle. 
How many vertebrae are there ? Note their lateral pro- 
cesses. Are any ribs attached? 
Note the medial dorsal spine, and the articular processes, 

joining the vertebrae. 
Examine a single separate vertebra. Is the solid part, or 

centrum, dorsal or ventral to the spinal canal ? 
The shoulder girdle consists of the shoulder blades, or 

scapulas; the clavicles, or collar bones; the coracoids; 

and the sternum, or breastbone. 
Which pairs are attached to the sternum ? The lower of 

these is the coracoid. Is the girdle fastened to the 

spinal column ? 
Identify in the shoulder girdle some cartilaginous regions. 

Where are they ? 
Locate the pelvic girdle. Of how many pieces composed ? 
What makes the frog humpbacked ? 
Compare shoulder and pelvic girdles. In what respect do 

they resemble each other, and how differ ? Are they 

homologous ? 
Examine the fore limb. The bones in order of position are : 

a. the upper bone, or humerus ; 

b. the united radius and ulna, between elbow and wrist, 
the radius being on the thumb side ; 

c. the carpals, or wrist bones ; 

d. the metacarpals, or hand bones ; 

e. the phalanges. How many of each ? 
Examine the hind limb. It consists of : — 

a. the upper bone, the femur ; 

b. the united tibia and fibula ; 

c. the tarsals ; 

d. the metatarsals ; 

e. the phalanges. 



THE FROG 97 

Compare hand and foot as to number and arrangement of 
phalanges. 

Are fore and hind limbs homologous ? How can you ac- 
count for their differences ? 

Why has a frog's hind limb so much freer motion than the 
fore limb ? 

Embryo and Tadpole. 

If freshly laid eggs are to be found, place some in each of 
several large jars of water with some water plants, and 
set in as many different conditions of light and heat as 
possible. 

What is the color of the eggs ? How are they held to- 
gether and protected ? 

Examine from day to day and draw as many stages of the 
embryo as you can discover with low power or lens, 
shading your drawings to show the difference between 
the dark and light regions. Date each drawing. 

Does a difference in conditions affect the rapidity of the 
development ? 

When the tadpoles appear, watch their growth in the same 
way, sketching the various stages in their metamorphosis 
and dating the sketches. 

Are they active at first ? How supported ? 

When they begin to move about, do they come to the sur- 
face of the water for air ? 

How do they breathe ? 

Examine an external gill with the lens and microscope. 
What is its structure ? 

How many pairs of gills ? When these disappear, can the 
tadpole leave the water ? 

It then breathes by internal gills. How does water reach 
and leave them ? 

LAB. MAN. ZOOL. — 7 



98 VERTEBRATA 

Watch tadpoles feeding. Do they use animal or vegetable 

food ? 
What changes take place in head and tail during metamor- 
phosis ? 
Which pair of limbs develops first? 
When the hind legs have appeared, dissect a tadpole and 

compare mouth and internal organs with those of the 

adult frog. 
When both limbs appear, does the young frog spend all the 

time in the water ? How can you arrange an aquarium 

to ascertain ? 
What advantages accrue to the frog from being able to 

adapt itself to a change of environment ? 

Advanced Work. Topics suggested for further study 

and discussion : 
(i) Examination of external features of toad, treetoad, 

salamander, and other Batrachians, and comparison with 

the frog and with each other. 

(2) Identification of the tadpole stage of each, and com- 
parison of their metamorphoses. 

(3) Hibernation of Batrachians. 

(4) General characteristics of the Class. 

THE FISH (PERCH OR ALLIED FORM) 

What is the shape of the body? How adapted for motion 
in the water ? Compressed or depressed ? 

The locomotive organs are fins. How many pairs ? 

Those homologous to the fore limbs are pectoral. Locate 
them. 

The other pair are called ventral or pelvic. Why ? 

How many unpaired fins ? The one on the back is the 
dorsal ; the one on the median ventral line, the anal. 



THE FISH (PERCH OR ALLIED FORM) 99 

The tail fin is the caudal. Is it bilobed? If so, are the 
lobes equal (homocercal) or unequal (heterocercal) ? 

Study the structure of the fins. They consist of rays, 
some of which are supported by bony spines and some by 
cartilage. How many layers of skin are between them? 

Examine the different fins and determine which rays are 
bony and which soft. 

The Head. 

Examine the mouth. In which direction is the opening? 

Does it resemble frog or crawfish in this respect ? 
Open the mouth and note the movements of the jaws. 

How different from those of the frog ? 
Are teeth present ? If so, where and of what character ? 

How do they point? 
Examine the tongue. Describe its size, shape, attachment, 

and surface. 
Note the shape and position of the eyes. Are eyelids 

present ? 
Compare the eyeball with that of the frog. Of what 

movements is it capable ? 
Examine the nostrils. How many ? Do they open into 

the mouth ? (Use a blunt probe to determine this.) 
What is their only function ? What two functions exercised 

by the frog's nostrils ? 
Can you find any external ear ? 
Look on each side of the head for the gill cover, the 

operculum. 
Raise this and examine the gills. Find the bony arch 

supporting the gill fringes, and the gill raker on the 

anterior of the arch. 
Thrust a scalpel in the mouth and depress the tongue. 

How does this affect the gills ? The gill rakers ? 

L.OFC, 



100 VERTEBRATA 

Between the gills are gill clefts which communicate with 

the mouth. 
How many gills ? Arches ? Clefts ? Rakers ? 
How does water reach and escape from the gills ? How 

can you determine this in a live fish ? 
Why does a fish lie with head upstream ? 
Describe the body covering. How are the scales arranged ? 

The skin covering them is the epidermis. 
Is the pigment which gives color to the body covering in 

the scales or in the epidermis ? 
Find a lateral line running along the side of the body. 

What forms it ? 

The Live Fish. 

Which fins are most- used in swimming ? In rising and 
sinking? This may be determined by binding down 
first the pectoral and then the ventral fins to see what 
difference it makes in the movements. 

Bind both pairs. Of what use are dorsal and anal fins ? 

Can a fish swim backward ? 

Can it remain stationary without moving the fins ? 

Have fishes any special resting places or positions ? 

What special senses are developed in the fish? Which 
are keenest ? How can you find out ? 

Can a fish live out of water ? Explain. 

Internal Organs. 

Examine a fish that has been dissected, to find the air 
bladder. Is this homologous or analogous to the lungs 
of higher animals ? Can you suggest its use ? 

Compare the other internal organs of a fish with those of 
a frog. 

How many auricles has the heart ? 



THE SNAKE IOI 

Is the circulation single or double ? 

The artery leaving the ventricle goes to the gills. Does 

the heart pump arterial or venous blood ? 
Are the digestive organs as well developed as in the frog ? 
Compare the brain with that of the frog. 

Advanced Work. Suggestions for further study and 

discussion : 
Examination of dogfish as to shape of body, snout, tail, 

and fins ; structure and position of latter ; body covering; 

mouth parts ; and arrangements of the gills. 
Food fishes and their economic importance. 
Artificial propagation. 
General characteristics of the Class. 

THE SNAKE 

A Reptile 

(A small live garter snake preferred) 

What shape ? Can you distinguish head ? Neck ? Thorax ? 

Abdomen ? Tail ? 
Are any limbs visible ? 

How does a snake move ? By means of what ? 
What body covering and how arranged ? 
What color? Is there any advantage in the coloring? 
Is there any difference in size and shape between the 

scales on dorsal and ventral surfaces ? Between the 

ventral scales on the body proper and those on the tail ? 
Are the scales closely applied to the body ? Are they 

covered with epidermis ? 
Locate the eyes. Are there any eyelids? Have the 

eyes any movement ? 
Are external ears present ? Are nostrils ? 



102 VERTEBRATA 

Can you see any breathing movements ? If so, describe 

them. 
Are the nostrils of use in breathing ? 
Is the sight keen ? 
Is hearing ? Is smell ? 

What sort of food does a snake eat ? Doe§ it eat often ? 
Describe the tongue and its use. 
Chloroform a snake. Open the mouth. 
Are the jaws closely hinged to the skull ? 
Why can the snake swallow relatively large objects whole? 
Are teeth present ? If so where are they and how do they 

point? 
Are they adapted for mastication ? Of what use ? 
With forceps draw out the tongue. Describe its arrange- 
ment. 
Find the glottis and the opening to the esophagus. 
The internal organs are more elongated than those of the 

frog, and only one lung is developed. Can you suggest 

a reason ? 
The heart is much like that of the frog. What cavities 

has it ? 
Examine a shed snake skin. Has it any color or markings ? 

How is the skin pulled off ? 
Draw a dorsal view of the snake's head and a part of its 

body. 
Draw a ventral view of the same. 

Advanced Work. Topics for reading and discussion : 

Venomous snakes. 

The cobra. 

The boa constrictor. 

Reproduction of the snake. 



LIZARD AND TURTLE 103 

THE LIZARD 

A Reptile 

In what respects does the lizard resemble the snake ? In 
what general features do they differ ? 

Compare the limbs with those of the frog in relative length, 
arrangement of joints, number of toes, and any other 
features in which they differ. 

Examine the scales on dorsal and ventral surfaces and 
compare with those of the snake. 

Locate the eyes. Are eyelids present ? 

Are there any nictitating membranes ? External ears ? 

If a live lizard is studied, observe and describe the move- 
ments of legs and tail. 

Are lizards easily captured ? 

If the tail is lost, does it grow again ? 

Advanced Work. Topics for further study and discus- 
sion : 

The horned toad. 

The heloderma, a poisonous lizard. 

Reproduction of the lizard. 

THE TURTLE 

A Reptile 

(A live animal preferred) 

The body covering is what ? The upper part is called the 
carapace ; the lower, the plastron. How united ? 

Observe the plates marking the shell. 

Describe the coloring. 

In the box turtle the plastron is divided by a hinge. Of 
what use ? 



104 ■ VERTEBRATA 

Are any scales on head and neck ? 

Examine the head. What kind of jaws ? Are teeth pres- 
ent ? Is there a tongue ? 

Examine the eyes. Are eyelids present ? Are nictitating 
membranes ? 

Is there any external ear ? 

Is sight keen ? Hearing ? Smell ? 

Are there any nostrils ? If so, where ? 

Can you see any breathing movements ? What animal 
does it resemble in this respect ? 

Study the legs. How many toes on fore and hind feet ? 

Is there a tail ? 

Does a turtle walk or crawl ? 

Compare turtle, snake, and lizard in external features. 
Why are all three classed together as reptiles ? The 
internal relationships are greater than the external. 

Advanced Work. Topics for further study and discus- 
sion : 
Alligators and crocodiles. 
Reproduction of reptiles. 

THE BIRD 

(A pigeon or game bird and a number of prepared skins of other species) 

What are the divisions of a bird's body ? Is any neck 

present ? 
What limbs are developed ? 
What body covering ? 
How is the shape of the trunk adapted for flight ? 

The Head. 

What range of motion has it ? 

Describe the jaws. The two divisions of the bill, or beak, 
are the upper and lower mandibles. 



THE BIRD 105 

Open the mouth. Are both mandibles movable ? 

Pull down the lower. Is it directly attached to the cra- 
nium ? Is the gape very wide ? 

Is the beak relatively long or short ? Stout or slender ? 
Blunt or sharp ? 

Is it hooked ? Conical ? Do the corners of the mouth turn 
down ? 

Are there any bristles at the angles ? 

To what is the build of the beak adapted ? Explain. 

Are there any teeth ? Is a tongue present ? 

Locate the nostrils. How protected ? 

Are eyelids present ? Nictitating membranes ? Of what use 
are the latter when present ? 

Look for the ears. Locate and describe. How protected ? 

The Wings. 

Are they attached to dorsal or ventral side of the body ? 

What advantage in this ? 
Make out three sets of feathers : 

a. the primaries, or pinion feathers, located upon the hand ; 

b. the secondaries, upon the forearm ; 

c. the wing coverts, at the base of primaries and second- 
aries arid covering the bend of the wing. 

With what joint in the human arm is the bend of the wing 

homologous ? 
Where is the elbow ? 
Is the humerus free moving ? 

The Tail. 

Does any part of the bony skeleton extend into the tail ? 

How supported ? 
How are the feathers arranged ? Is the tail forked, blunt, 

or wedge-shaped ? 



106 VERTEBRATA 

Of what use ? * 

The feathers on the body proper are contour feathers. Do 

they cover every part ? 
Lift and examine their attachment. To what fastened ? 

How ? 
Measure the bird from the tip of the beak to the tip of the 

tail. Next measure the wing from the bend to the tip, 

and the tail from its attachment to its tip. 
Compare these measurements in several specimens. What 

is the average length of the bird ? Of its wing ? Of the 

tail ? 
Describe the color of the plumage. 

The Foot. 

How many toes and how arranged ? 

Compare the length of the hind toe with the longest of the 
others. 

Is the fourth toe capable of being turned so that the ar- 
rangement may be 2-2 or 3-1, according to use ? If so, 
this toe is said to be versatile. What advantage would 
this give ? 

Is the foot adapted for perching, scratching, swimming, 
climbing, or tearing prey ? Explain. 

The tarsus, or foot, of the bird consists of a single piece, a 
consolidation of tarsal and metatarsal bones. 

Does the bird place the tarsus on the ground ? 

Where is the heel ? Knee ? 

Is. the femur free ? 

What covers the tarsus ? Is the covering a network (re- 
ticulate), covered with a few overlapping scales (scutel- 
late), or without distinct divisions (booted) ? 

Is it rounded behind or terminating in a sharp ridge ? 

These peculiarities of beak, feet, wings, and tail, of color 



THE BIRD 



107 



and markings, and of length of the body, legs, neck, 
wings, and tail, serve to distinguish different Orders, 
Families, Genera, and species of birds. 

Pinion Feathers. 

Identify quill, shaft, barbs, and barbules. 

Barbs and barbules together constitute the vane. 

Examine barbules with 1. p. How are the barbs held to- 
gether ? Why ? 

Compare one of the small, soft feathers, called down, with 
the pinion feather. 

Compare a pin feather from the breast. 

In what respect do they differ ? 

Of what use are feathers ? What purpose do they serve 
better than do the scales of fish and reptiles ? 

The Egg. 

(Fresh hens' eggs will serve the purpose of this study.) 

What general shape ? What outside covering ? 

Place an egg on the table and then in water. Which end 

is higher in each case ? 
Place the egg in a pan of water so it cannot roll ; mark 

the highest point, and boil hard. 
Break the shell and put a bit in acid. Of what composed ? 

Examine the lining. What is its character ? 
Does the egg completely fill the shell ? Where is the air 

space ? 
Break the shell at this place. Is the membrane single or 

double ? 
Cut the egg lengthwise, as nearly as possible in halves. 

What surrounds the yolk ? Is it of uniform thickness ? 
How is the yolk located? 
Prop another egg in water with the small end up, and boil 



108 VERTEBRATA 

hard. Compare the position of the yolk with that in 

the first egg. 
What is the position of the yolk in an egg in the nest? 
Break a raw egg carefully so as to divide the shell into two 

cups. * 
Drain off as much of the white as possible without break- 
ing the yolk. 
Keeping the yolk in one half of the shell, look for a light, 

eyelike spot. If not seen at once, turn the yolk into 

the other half of the shell. 
This spot is the germinal disk, in which segmentation takes 

place to form the embryo. 
Towards which end of the egg does it lie ? 
The remainder of the egg is absorbed as nourishment by 

the developing embryo. What kind of foodstuff is the 

white ? 
Test the yolk for fat. Does it contain any ? 
What conditions are necessary to the hatching of the egg ? 
What advantage in having the germinal disk near the 

upper side as the egg lies in the nest ? 
What advantage in the air space ? 

Advanced Work. Topics suggested for further study 
and discussion : 

Protection of birds by law J ' , . , " 

[o. game birds. 

Their economic importance. 

Migration. 

Nesting. 

Introduced birds. 

Characteristics of birds ; characteristics of principal Orders. 



A MAMMAL 109 

A MAMMAL 

(The rabbit, squirrel, rat, mouse, cat, or dog, or any other small four- 
footed animal will do.) 

The Body Covering. 

Of what does it consist ? 

Describe the coloring. Is it advantageous ? If so, how ? 

Is all the hair alike ? If not, on what parts is it longest ? 

Describe and locate the different kinds. 

Where is the skin bare ? 

The Head. 

Locate the eyes. 

Examine the pupil. What shape when relaxed ? When 
contracted ? 

Describe the eyelids. Is any nictitating membrane present ? 
If so, how well is it developed ? 

What additional protection has the eye, which is not pres- 
ent in any lower form ? 

What part of the ear is developed that is not in the lower 
animals ? Can you see the drum membrane ? 

Locate and describe the nostrils. 

Are the lips peculiar ? If so, how ? 

Open the mouth and examine the teeth, consisting of : 

a. the incisors, or chisel-like teeth ; 

b. the sharp single-pointed canines, used for tearing food ; 

c. the premolars or bicuspids, usually with two cutting 
points ; 

d. the molars, with broad roughened or ridged surfaces 
for grinding. 

Are all sets present in your specimen ? 

How many of each set ? 

How are the teeth adapted to the food of the animal ? 



HO VERTEBRATA 

Of what movements is the lower jaw capable ? 

Examine the tongue. How and where attached ? Of 
what composed ? 

What difference between the surface in anterior and pos- 
terior regions ? 

Look on the sides towards the back for an area containing 
taste buds. Examine with a lens. What is the shape of 
a bud ? 

The Limbs. 

How many toes on each foot ? 

Compare the claws on hind and fore foot. For what pur- 
poses used ? 
Are the feet padded ? 

Compare fore and hind limbs as to length. 
Are they better adapted for running or for leaping ? 

The Tail. 

What is its relative length as compared with the body ? 
With the tails of other animals ? Of what use ? 

The Breathing. 

What movements are concerned in breathing ? Is the air 
swallowed ? If not, how is it drawn in and how expelled ? 

Compare the rat, deer, cat, bat, and horse as to body 
covering, development of limbs and feet, mouth and 
teeth, other defensive organs, and reproduction. 

Why should they be classed together as mammals ? 

Compare the cat, lion, dog, and wolf. Why are they all 
classed among Carnivora ? 

Why are the cat and lion in one family, while the dog and 
wolf are in another ? 

What characteristics are possessed in common by the fish, 
frog, snake, lizard, turtle, bird, mammal ? 



VERTEBRATE SKELETONS III 

VERTEBRATE SKELETONS 

Compare the skeletons of the foregoing animals and man 
as to the following points : 

The Spinal Column. 

Number of vertebrae and shape of each ? 

Is the centrum concave or convex on its anterior surface ? 

On the posterior ? 
Are neck, dorsal, lumbar, and tail vertebrae all present ? 

If so, how do they differ from one another ? 
Are any of them very peculiar ? If so, how ? 
Are any fused together ? 

What advantages gained by these adaptations ? 
Are any other bones found in the spine ? If so, how many 

and where ? 
How many ribs and how attached dorsally ? 
Is there a sternum? Is it flat or keeled? Are ribs 

attached to it ? If so, how many and how ? 

The Skull. 

Are both jaws movable ? 

Is the lower jaw directly attached to the cranium, or is 

there an extra bone, the quadrate, intervening ? 
Is any other skull bone movable ? 
Examine the cranium. The irregular fixed joints are called 

sutures. Are they apparent ? 
Notice the opening through which the spinal cord joins 

the brain. The bone which surrounds this is the occipital. 
Prominences on this which rest on the first vertebra* are 

called condyles. Do you find one or two ? 
What kind of movement will this joint give ? 
Notice the shape of the cranium. How is it related to the 

development of the parts of the brain ? 



112 VERTEBRATA 

The Shoulder Girdle. 

How many and which bones are developed? How and 
where attached ? What kind of a joint with the humerus - ? 

How do the hip bones differ in different animals ? What 
kind of a joint with the femur ? 

The Fore Limb. 

Are ulna and radius separate bones or are they partly 

united ? 
Locate radius and ulna in your own right arm. 
Stretch the arm out before you with the palm of the hand up. 

Grasp the elbow firmly with the left hand and turn your 

right palm down. How is this accomplished ? 
Bend the elbow, with the hand first in one position and 

then in the other. 
Repeat these movements with the bones of hand and arm 

of the human skeleton. Is the fore limb in any other 

animal that you have studied capable of this variety of 

movement ? 

The Hind Limb. 

Compare with homologous parts of the human leg. 

Can the sole of the foot be turned up or forward ? Explain. 

Compare with the limbs of other animals. 

Explain the advantages in the adaptations in each case. 

Hand and Foot. 

Compare the homologous bones in the human hand and 
foot, including wrist and ankle. How do they differ ? 

What difference in freedom of movement between thumb 
and great toe ? 

What animal can you think of whose hind feet are some- 
what like the human hand ? Of what advantage ? 

How many carpals, metacarpals, and phalanges, are de- 
veloped on the fore limb ? 



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